Grumpy Help! Torque: Hot, Nasty Torque: FIRST Fuel Injection Intake SBC Build

NewbVetteGuy

NewbVetteGuy

Well-Known Member
I THINK I've read what little is out there regarding the FIRST Fuel Injection TPI-style (but not performance) SBC intakes. I've read all the Grumpy's threads on the subject, to my knowledge and the major build threads on the ThirdGen site, but I still have questions that I'm hoping Grumpy can answer, as there's just not a lot of people out there with experience or in-depth analysis of this intake.

Background (My Car): I've got a single-family 1979 L82 Corvette that I was recently given by my parents who bought in the car in 1979. Originally they bought "his and hers" C3 Corvettes: a 1978 L2 manual for my dad, and a 1979 L82 automatic with all the option except for the CB for my mom. Then I was born in 1980 and my sister in 1982; my sister was diagnosed with cancer before she was 1 year old so they sold the 78 to help with the hospital bills, but kept the 79 forever, although it rarely if ever got driven or plated. I was given the car early this year with 13,600 miles on it after it had been sitting for about 12 years; it required a LOT of love from a mechanic to get it up and running again.

My goals:
Goals
[*] Plenty of fun, tire-burning low to mid RPM torque- in Grumpy and Lingenfelte style
[*] Longevity/ reliability -this is a family car with only 14.9k miles now; it's been in my family almost 40 years and I'd love to see it stay there for another 40 years; I don't plan on beating the crap out of the car and dumping it on someone else; reliability is important
[*]Increase in fuel economy vs. stock L82 (my 4L60e transmission's overdrive and lockup torque converter will help, as will the EFI, but I don't want the cam to be too crazy and just completely kill fuel economy)
[*] Given my previous goals; don't leave too much extra HP on the table "wasted" -the heads have so much potential
[*] Also in Grumpy style, to properly plan this build in detail so I don't have to learn something the "hard way" -my wife is only going to let me do this once
[*] I want to be in decent shape to be able to get even more tire-shredding torque if /when anything requires the bottom-end to be rebuilt in the future- I'd like to keep the numbers-matching original block and make it a Stroker 396, or 383, if the budget absolutely required it- 396s are just so much rare and cooler, IMHO


"Knowns" in my build:
[*]GEN1 L82 SBC 350 (good bottom-end to build off of)- I'm looking to have an entirely new top-end and not touch the bottom-end right now
[*]Heads: ATK's casting of the Profiler aluminum heads 64cc combustion chamber; 195CC intake- I've been told that the flow numbers are not over-inflated but, who knows; I've read Grumpy's opinions on head intake ports not actually creating huge issues with low RPM torque in a well-planned build, but as I will be living with this as an SBC 350 for hopefully quite a few years, I need to still have the torque while it's an SBC 350 and I think these heads have plenty of flow to scale up to 383 or 396, given my focus on torque and not max HP. If I need to get them ported or CNCed larger when I go the stroker motor; or completely ditch them for larger heads, I can get to that bridge then.

Note: The ATK casting of the Profilers have reduced exhaust flow #'s because they're standard height, standard sized exhaust ports; I'm ok with this as fitment with my existing FlowTech 1 5/8th headers is important to me. I'll just go with a larger duration on the exhaust lobe on my cam to make up for it.

Lift CFM Lift CFM
0.200 144 0.200 107
0.300 207 0.300 142
0.400 250 0.400 172
0.500 268 0.500 187
0.600 270 0.600 196
0.700 271 0.700 203
[*]Exhaust: long tube headers 1 5/8" with 3" collector down to 2.5" true dual exhaust (Flowtech Coated), H-pipe, no cats, high flow mufflers
[*]Intake: FIRST Fuel Injection intake- not sure on what to have done to it...
[*]Curb weight 3,650lbs but down to 3,400-3,450 when the top-end goes in (lighter weight battery, spare tire removed, Steeroids rack and pinion conversion, composite rear spring)
[*]4L60e Monster Transmission with super torquey low 1st gear (computer controller version of a 700r4) -Stage1 build built for 450ft lbs of torque
[*]2,300-2,500 lockup torque converter with carbon lockup clutch; quality from Monster.com but still a 12" factory physical style
[*] TCI EZ-TCU trans computer to control shift points, shift firmness and lockup strategy (fuel economy and performance improvement & configurable)
[*]4 row aluminum radiator to keep temps cool -mentioning because hoping it will help with reducing pinging risk- Chinese "Champion"
[*]Cold Air Intake-not sure what to get but this will happen; I refuse to give this up and my dynamic compression is right around 8.5:1 so I'll need the cold air to help keep detonation at bay
[*]I'm willing to run premium fuel, if necessary 91 octane is readily available, 92 if I hunt for it; 93 doesn't exist in Washington, really
[*]EFI system will be going in this winter/spring- The Holley Terminator /HP is widely available used and will support a sequential multi port setup which is what I would like. I also want ignition control and electric fan control, so Holley or FAST are definition options. The FAST integrates well with my trans controller, too.
[*]355 rear gears
[*]I've pretty much settled on retrofit hydraulic rollers and a roller cam; If I have to go with the Morel Cheapos that only support lower RPMs, I will, but I'd love to get a higher RPM-capable set if I can find a deal- I keep looking
[*]Quality steel or stainless steel roller rockers
[*]"Appropriate" roller cam springs
[*] Static CR with FelPro 0.015" gaskets = 10.1-10.2


I'm looking for some detailed recommendations on the FIRST Intake and whether it's going to out-of-the-box be a huge power limitation for me and what RPM I can expect the torque peak at. I've seen mixed results from flow meters reported with the FIRST intake; Grumpy's reported huge POTENTIAL when ported out of this thing, but I really am curious, at least for my 350 build, what the flow is like out-of-the-box. I've heard that there's some issues with a couple of the runners and that the flow through runner 8 could be as low as like 221 CFM; with my heads flowing 268CFM @ 0.500" lift that would be a HUGE restriction to airflow and would (I think) lower my torque peak and HP curve peak rpm (and therefore total HP).

I tried to use DesktopDyno but the flow numbers varying at inches mercury vs. inches of air just confused the hell out of me. I'm not sure if when I do the calculation I should use the air flow reported by the poorest flowing runner or if I should go with the average. (Either Ezobens's flow bench results from here aren't awe-inspiring: http://www.thirdgen.org/forums/tpi/687060-megaram-first-ffi-tpi-2.html)

I can tell from some dyno results how much HP I stand to lose vs. a normal dual plane intake, but I'm not really sure how much torque I stand to gain by going with the FIRST, either so even an hp/ torque cost benefit analysis is difficult, currently.

I'm also very much interested in CAM recommendations. I originally posted my goals and build details on Speedtalk.com- thinking I'd go with a typical dual plane intake and Mike Jones responded with a cam recommendation of:
Cam# SBCR, HR68340-69340-110
264/268 @.006"
216/220 @.050"
.340"/.340" Lobe Lift
.510"/.510" Valve lift
110 LSA
107 ICL

And then clarified in another thread that he'd usually recommend a slightly increased LSA or duration, but didn't provide any specific details as obviously the custom cam guys really make money by you buying the cam from them so they don't want to provide too many details. -I'm interested in learning and I can't really get the custom cam guys to provide any details or WHY they'd recommend those changes from the cam when going to a FIRST TPI-style intake...



I realize if I end up having a shop do a 383 or 396 conversion for me later that I'll need a bigger cam and I'll need dished pistons to keep the CR at the acceptable level, I'd need a new oil pan; I know that going beyond 383 means a forged crank and probably forged pistons if spinning above 6,000 RPM may ever happen; I'm also assuming that a 383 or a 396 and beyond 6,000 RPM probably wouldn't work well with my 195cc heads, so I really probably should assume an RPM max of 6,000 anyway. -I'm also afraid I'd probably be reaching the limitations of my 1 5/8" full length headers with a 396 build topping out at 6,000 RPM, too.

What else do I need to know? Anything I screwed up? (Again any Stroker motor I hope is at least 5-10 years in my future; so SBC 350 for this build.)


Adam
 
Welcome to the forum Adam.
Looks like you're really focused! Does your '79 have the front airdam and rear spoiler? What color? Oh Wait, you're going to send pictures right? LOL!
 
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chromebumpers said:
Welcome to the forum Adam.
Looks like you're really focused! Does your '79 have the front airdam and rear spoiler? What color? Oh Wait, you're going to send pictures right? LOL!
Click to expand...
Black exterior and interior, but the paint was never that great; not even from the factory.

Front air dam and rear spoiler.

Unfortunately my only pictures were on my phone that took a swim... Car is in rural Indiana at a shop getting the headers installed, 4l60e swap, and Steroids kit installed. Then it gets shipped out to me in Washington State.



Adam
 
PDRM1966a.jpg

http://garage.grumpysperformance.co...ive-are-the-stock-tpi-engine-components.1509/

since your stating your main concern is getting as much mid rpm torque as possiable from your engine the first intake would be my choice, but it will require port matching to decent flowing heads,long tube headers and a full 3" and 3" (X) pipe exhaust,
the flow numbers you posted for those heads listed look ok,you seem to be on the correct basic path,

Lift CFM Lift CFM
0.200 144 0.200 107
0.300 207 0.300 142
0.400 250 0.400 172
0.500 268 0.500 187
0.600 270 0.600 196
0.700 271 0.700 203
obviously youll want a cam with the duration and lift to allow the ports to flow to thier potential limits, without the slightly increased duration and the 1.6:1 roller rockers the valves can,t remain open far enough or long enough to reach the port and runner and cylinder heads flow potential, and any restriction in exhaust flow like the 2.5" pipes after the collectors will show in lost torque due to less effective cylinder scavenging, efficiency,that of course requires matched components, in this case Id have suggested a bit more cam, and 40 lb fuel injectors
example
http://www.herbertcams.com/500-500-lift-225-235-dur-050-112-lobe-center/
port matching the intake to the heads after having the intake extrude honed and use of 40 lb injectors seems to be a logical route to take here
http://www.extrudehoneafm.com/faqs/faq-automotive/
and 1.6:1 roller rockers and a 3.54:1-3.73:1 rear gear ratio and a 383-406 short block and heads that flow well with long tube headers , with 3" exhaust (not 2.5")

http://garage.grumpysperformance.com/index.php?threads/is-backpressure-hurting-your-combo.495/

http://garage.grumpysperformance.com/index.php?threads/x-or-h-pipe.1503/

http://garage.grumpysperformance.com/index.php?threads/calculating-required-exhaust-pipe-size.11552/

http://garage.grumpysperformance.com/index.php?threads/calculate-fuel-injector-size.1200/

http://garage.grumpysperformance.com/index.php?threads/how-big-a-fuel-pump-do-you-need.1939/

http://garage.grumpysperformance.com/index.php?threads/input-on-electric-fuel-pump-selection.10664/
 
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Thanks!

Additional context before I ask some clarifying questions: Although I grew up around cars and chevy performance stuff and talk; most if it went in one ear and out the other. I never really cared nor bothered to learn much beyond what basic engine / car parts do. Since being given this car I started trying to learn as much as I could, especially started in June. I've spent way more hours per week than I'd like to admit to my wife or my boss on it, but there are still HUGE gaps in my knowledge and understanding and I'm definitely afraid that I'm missing or mis-applying something important. I've learned a couple things in pretty good depth but I have huge knowledge gaps that I'm afraid might sneak in and screw up my build if I don't get knowledgeable people to give it a second look.

Goal Clarification/ Addition: I'd REALLY like to hit 1.2:1 ft lbs per cubic inch on this build or get as close as I can; torque == hp would be great. I'd love to see 425 ft lbs and 420 hp but if I have to give up HP to get more torque and fuel economy, then that's fine, too; I realize this might be a slightly optimistic goal with my old bottom end -I'd feel more confident that I could hit it with total seal rings but that will wait for the stroker rebuild.

Questions:
1. Is the recommendation for 3" dual exhaust applicable even for just my top-end rebuild today, or will the exhaust only really be a restriction later if I go to a 383 / 396 stroker? (I'm not questioning your feedback; I'm just questioning whether you meant for it to apply to the stroker version of the engine or the 350 version or both.) -If the current 2 1/2" dual exhaust is a restriction; would exhaust cut-outs prior to the mufflers help much? (If I was going to the track or really wanted to put the car in "performance mode" I could just bypass the restrictive exhaust and mufflers and let it be loud and fast for a while -that's my thought of a cheap partial solution.)
2. Is getting the FIRST intake extrude honed a recommendation for my current top-end rebuild with just 350 in3 or is that something that would only be required after moving to 383 / 396 in3?
3. I think the most help I need is in "doing the math" right now and determining where my airflow restriction is and what my hp / torque curves might look like now and what I could do to improve them. -I tried to use Desktop Dyno but I didn't really have good airflow numbers for the intake and I didn't know how to convert from inches mercury to inches air, etc... I was also trying to use some other calculators that looked at the intake runner lengths and cross sectional area to estimate the torque curve / hp peaks but I couldn't find information on the cross-sectional area of my heads anywhere. (The ATK Profiler casting and the regular Profilers have identical intake ports; it's only the exhaust that's different.) --the stock FIRST intake has a 2.4 sq inch cross section, but I have no idea whether the heads have a larger or smaller cross section than that or how that would effect the HP peak / curve
4. For my goals would just a modest "cleanup" of the FIRST intake get me there or do I need to spend a ton of money getting it more significantly ported / extrude honed for even my 350 build?
5. The COST of the FIRST intake is well-known, but what kind of ft lbs of torque "return on invcstment" can I expect to get by going with the FIRST intake vs. a run-of-the-mill dual plane intake- say a Performer or Performer RPM? (The airgap won't fit under my C3 hood) -If we're talking about a 40 ft lb improvement; let's say the fly wheel torque with a Performer intake was 360 ft lbs and the FIRST intake would get me to 400 ft lbs and provide torque benefits over that 1800-5800 rpm range then it's totally worth it to me; EXACTLY what I'm looking for; I'm just not sure even what to expect; Ken from First REALLY doesn't want to share any customer's dyno results before and after which honestly is one of the things slightly concerning me...

I've read your "How Restrictive are the stock TPI engine components" thread quite a few times, but I'm still a bit fuzzy on a few details:
1. What is the flow of the FIRST intake? (There's numbers for every other TPI-style intake out there, but the FIRST is missing)
2. What is the runner length of the FIRST intake? -I think I read somewhere else that it's a few inches shorter than the stock TPI intake but not by much and I can't find that post anywhere either
3. What is the stock torque peak and HP peak / range of the FIRST intake? (I think you said 4,800 RPM torque peak on a 350 but it's slightly ambiguous; I think you said the larger torque curve range for the FIRST should be 1800-5800 on a 350 but I don't know about HP at all.)




You said that the stock TPI intake is "optimized" for 3400 RPM on a 350- is this the torque peak or HP peak? (I'm assuming torque); you said that the FIRST intake is optimized for 4800 RPM on a 350 with its stock 2.4 sq inch cross section -that's torque, right?


Adam
 
On the 1.6 RRs, do you recommend 1.6 on both the intake and exhaust, give my head's mediocre exhaust flow numbers, or just on the intake side? I've seen so many recommendations for 1.6RR intake / 1.5 RR exhaust on SBC heads that I have to ask.


Adam
 
I've generally had better results with 1.6:1 ratio roller rockers on both intake and exhaust locations.

you can calculate both ideal port size and port stall size, (rpm where ports very restrictive to flow)
the FIRST intake is well matched to the cam I linked
http://www.herbertcams.com/500-500-lift-225-235-dur-050-112-lobe-center/
matches your particular application


http://www.wallaceracing.com/runnertorquecalc.php

https://www.rbracing-rsr.com/runnertorquecalc.html

http://www.wallaceracing.com/chokepoint-rpm.php

same with headers

http://www.wallaceracing.com/header_length.php
 
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Thanks, again; my problem is that I'm just too stupid to use those calculators; I don't know the required information to use them

I entered "350" cubic inches, 8 cylinders, 2.4 square inches intake runner area (not sure if I'm supposed to enter the intakes runner area or the head's intake runner area or the lesser of the two there- but it shockingly spit out a healthy 4,838 RPM

Then I tried to calculate "Optimum Runner Size and Length" -not sure why I would as the runner length is what it is, but I have no idea what to put in for "# of Induction Waves"; I think this is where I'm supposed to know that because I'm looking to maximize torque that I should know which wave it is that optimizes torque and enter that number (somewhere in the 2-4 range, I think)- but I actually don't know that number and there's no "help" link in the tool.


Adam
 
 
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Adam, DorianL will want to know about your Steriods installation for his chrome pumper vette.
 
Thanks again, Grumpy. Your cam recommendation is starting to feel more right now as I focus on understanding WHY you made this recommendation vs. just comparing to the MikeJones recommendation for a slightly different build.

The wider LSA seems to make sense, both because I always hear wider LSAs being recommended for TPI-style intakes AND because it helps with a nice wide fat torque curve that also "pairs well" with a TPI-style intake (maybe this is why wider LSAs are recommended for long-runner tuned intakes?).

The increased duration also seems more reasonable; seem like 1,500-5,500 rpm range per the CID per cylinder chart. I might have been giving up a bit too much top-end with the previous smaller duration recommendation.

One thing I was shocked by was just how large of a duration separation your recommendation had vs. Mike Jone's (255/235 -10 deg split vs 216/220 -4 deg split), but then I realized that I was looking at the ATK Profiler 185cc heads then and the split between intake vs. exhaust flow was much smaller on those heads vs. the 195ccs that saw only improvement on the intake side, so that really makes sense.


I still don't understand the exact valve timing events and their relevance and all the trade-offs involved but I'm ok to go with the opinion of an expert on this one. Unfortunately your recommendation to go with a 0.500" lift (at valve) cam and 1.6RRs puts me in a bit of a bind (pun intended) as the springs that come with my heads support a max lift of 0.600". I'll probably have to pay to get upgraded springs, but I'm ok with that.


I should mention one more possibly important detail that I left out: My 4L60e transmission's 4th OD gear runs at a 0.70 ratio and with my tire size and rear gears that puts me at 2,166RPM @ 70 mph and 1702 RPM @ 55mph with the TC locked up.

The CID per cylinder chart indicates that the cam's bottom end is about 1,500 RPM, although the "cam card" stats say 1,200-6,200; it's also my understanding that the higher the cross sectional area of the intake, the higher that the RPM range gets bumped up. Does the larger cross sectional area of the FIRST intake possibly start to cause me issues with my 1702 RPM 55 mph cruise? (If the larger cross sectional area bumps that 1,500 RPM up to say 1,800 RPM.)

-If I understand correctly, I think I can slightly tweak my torque curve by adjusting the cam to crank timing -I think one of your articles said 300 rpm per 2 degrees of advance --just theoretically if I found myself cruising all the time at 55mph and 1702RPM and the engine started to bog a bit, I could advance the cam 4 degrees and drop the start of my curve by 600 RPMs and solve that problem? (and possibly increase my fuel economy at cruise by getting closer to my torque curve and efficiency sweet spot?)

I can't believe I wasted 35 years of my life avoiding learning about this stuff; it's awesome!


Adam
 
chromebumpers said:
Adam, DorianL will want to know about your Steriods installation for his chrome pumper vette.
Click to expand...
Ok, I'm not sure I'll have much information for him, but he can ask away. I've got another 2 weeks before it goes in, though.

Definitely check the Steeroids site for fitment issues, particularly with headers. The normal Hooker Comps and Super Comps work perfectly as do the Flowtechs; many others require minor dimples and quite a few side pipes have HUGE issues; Hedman headers can be just completely unusable, from what I've read.


Adam
 
I'M RATHER WELL EXPERIENCED , after 45 plus years of engine building and helping out on dozens of performance car builds, BUT I don,t consider my self an expert
I've always suggested you discuss and cam and valve train components and cylinder head choice along with the drive train gearing, that FIRST INTAKE MANIFOLDS manufacturer, your going to buy and install with the cams ,manufacturer, heads, manufacturer, torque converters etc. manufacturer, etc.
youll want several well experienced people giving your total combo a detailed look over and making suggestions, once each considers the combo as the components are listed and they compare their experience with similar combos

http://garage.grumpysperformance.com/index.php?threads/semi-fool-proof-cam-sellection.82/

http://www.herbertcams.com/500-500-lift-225-235-dur-050-112-lobe-center/

http://garage.grumpysperformance.com/index.php?threads/my-current-corvettes-383-combo.430/

crane (386)310-4875

crower 619.661.6477

erson 800-641-7920

lunati..662-892-1500

ISKY 323.770.0930

clay smith 714-523-0530

herbert cams 714-491 -2267
 
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Oh my! My long lost twin project...

Wait, is that an otter with a beer?

I seem to be going a route parallel to yours... albeit with a slightly different approach. I plan to go for a 496 BBC, I will have a manual 4 that will become a manual 5 (or 6) one day... and then there is the Steeroids.

I am thinking a full-monty Shark Bite (with rims and tires to match) conversion; this car will be expected to take on at least once a week street duties. Brakes for sure and of course the rack and pinion... for me that will be the priority: getting this C3 to handle and stop.

Whatever you can provide as feedback regarding the suspension, brakes and steering is VERY WELCOME!!!! From installation to effectiveness on the road!

To quote the spooks over here: I am watching you!
 
hey Adam I was stuck on the 396 idea for a while not worth the cash to make it happen!!! The cost per hp and ft/lb between 383 and a 396 street engine is insane. You can do a real nice 383 for a decent price. Do your homework grumpy has it all here in the forums for you to learn, read the links. Do it right there is more to meets the eyes with efi and tuning. I am in the middle of a efi conversion on my chevelle. Build a proper fuel system for your needs also.
 
Strictly Attitude said:
hey Adam I was stuck on the 396 idea for a while not worth the cash to make it happen!!! The cost per hp and ft/lb between 383 and a 396 street engine is insane. You can do a real nice 383 for a decent price. Do your homework grumpy has it all here in the forums for you to learn, read the links. Do it right there is more to meets the eyes with efi and tuning. I am in the middle of a efi conversion on my chevelle. Build a proper fuel system for your needs also.
Click to expand...

Yea, at initial glance the cost jump from a 383 stroker kit to a 396 looks HUGE. BUT if you're looking at a 383 stroker kit with a forged scat crank, forged pistons, and forged h-rods, then the costs seem almost identical.

Longevity is SUPER important in my build as the car's been in my family for 40 years and I want it to last. -My car's L82 motor came with all forged components and if I'm replacing the bottom-end, I want to replace it with components of equal or greater quality.
I also like the idea that if I go with a forged bottom end, the engine can support spinning up to higher RPMs if I decided to also select valve train components (and a TC stall speed) that supported them, too; a nitros kit could also be safely supported. --I like the idea of having OPTIONS especially with the bottom-end components that really should last as long as possible. I might over-build the bottom-end and "waste" money there, but if I'm going to over build and "waste" money anywhere, I think it should be in the bottom-end and maybe the heads.



I definitely see what you're saying from a value perspective, especially if I set a rev limiter to 6,000 RPM with a 383- then forged internals is probably over-kill and about $1,000 "wasted"... It's a tough choice. One I won't need to make for a long time, I hope....


Adam
 
DorianL said:
Oh my! My long lost twin project...

Wait, is that an otter with a beer?

I seem to be going a route parallel to yours... albeit with a slightly different approach. I plan to go for a 496 BBC, I will have a manual 4 that will become a manual 5 (or 6) one day... and then there is the Steeroids.

I am thinking a full-monty Shark Bite (with rims and tires to match) conversion; this car will be expected to take on at least once a week street duties. Brakes for sure and of course the rack and pinion... for me that will be the priority: getting this C3 to handle and stop.

Whatever you can provide as feedback regarding the suspension, brakes and steering is VERY WELCOME!!!! From installation to effectiveness on the road!

To quote the spooks over here: I am watching you!
Click to expand...


I don't know enough about suspension or brakes to really provide any advice. For steering, I knew that I would have a lot of work to do replacing bushings and getting the stock sloppy steering box blue printed to get it tightened up and to where I wanted it and there were still no guarantees. A borgeson box conversion was an option, but the cost starts to get very close to a good Rack and Pinion system and the rack and pinion installation just involves pulling off the old stuff and bolting on the new stuff. It saves weight, too and has a very modern and slop-free feeling. Like I previously mentioned clearance for headers must be planned for and I think you may have far bigger challenges with a big block so plan accordingly there. I also wanted faster steering with fewer turns lock-to-lock -some people don't like this aspect of the rack and pinion conversions, but as I'm planning on adding paddle shifters, I think this is a positive attribute of the rack an pinion system. Bump steer is also a scary issue that plagues these old steering systems and it can be tuned out during the install of the rack and pinion systems. -Also know that your turning radius will be negatively impacted if you go with a rack an pinion system. I'm assuming with huge big block torque and weight you have no plans to auto-cross your car, but if you want to maintain the from-the-factory turning radius your most radical available steering upgrade is the borgeson box conversion. Also beware that the borgeson box puts more pressure and more leverage on your frame and stress fractures of the frame under spirited driving / cornering could result if you don't brace things correctly. There are aftermarket braces available that can help (or build/weld your own) but these will cause tire rub with 255 width or larger tires when the wheel is turned all the way so beware that problem. -Also remember that wheel tolerances vary significantly from year to year with the C3s so measure, measure, measure; the general rule is that things are tighter with earlier C3s and you've got more room with the later C3s.

The VB&P Rack Attack kit is the most expensive but their system has the most appropriate heavy duty brackets, IMHO. The Steeroids, from my research, is the 2nd best option and I bought mine 2nd hand yet still new-in-box at a significant (35%) discount, so it was a no-brainer.


If you're looking to go with a hydroboost brake conversion for your C3 corvette to avoid reliance upon the vacuum system, then you REALLY need to research and plan because lots of people have run into challenges with the power steering racks and brakes running off of the power steering pump. They have different pressure requirements and even the hoses are rated for different pressures so be careful with this combo.



I've heard nothing but good things about going with a full Wilwood aluminum high perf 4 disk brake conversion + new master cylinder and booster and new stainless braided lines but it's $$$$ EXPENSIVE and at my current perf levels, the stock system well maintained with performance pads is more than acceptable.


Adam
 
With the steering / R&P conversion there's also the issue of U-joints for the steering column or using the rag joints... For longevity, a lot of people swear by U-joints but they allow more vibrations to transfer through the wheels and into the steering wheel. Finding high quality rag joints today is apparently a challenge, and although they don't have the same longevity / reliability of a simple solid u-joint, they can help maintain a more stock steering feel with less vibrations. (Although obviously the steering system won't' feel stock with a rack and pinion conversion-- much better than stock.) ;-)

I'm going with U-joints and am just hoping that good modern shocks will handle the bumps. If I absolutely hate it, I could switch it back to rag joints easily enough.


Adam
 
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