Walde's -86 L98

W

Walde

Well-Known Member
Greetings from Finland, Grumpy & co.

Please, bear with me with the background, it's a longish yada-yada-story but might describe the situation:

I have a basically stock -86 L98 Vette with 4+3 transmission. The final ratio is 3.31:1 (or so) and I have 65k miles on the clock. Just about everything on the car works apart from noisy AC compressor and worn throttlebody. Car still has functioning AIR and EGR but precats and main cat have been gutted. Original mufflers have been replaced with KBD Targa mufflers by earlier owner. Sound is very nice and performance adequate considering I'm getting over 25 MPG on the highway in OD.

I have been thinkin about making some minor mods to the car - surprise, surprise - to increase performance a bit. I drive mainly on the street with couple of track days each season. I have never drag raced as it just is not my cup of tea.

I have decided to make following things for next season:
  • cats gutted (done)
    remove AIR
    remove EGR
    replace throttlebody
    install headers
    replace injectors
    have it dynoed and re-chipped

For headers I'm getting Melrose 86-91R kit sans cats, see below:

melrose8.jpg


These are with 1 3/4" primaries. I would have preferred 1 5/8" but none of the so called quality brands don't seem to make them anymore.

I was wondering if I would continue a bit with the mods and get a heads-cam-intake upgrade while I'm at it. Now we come to my dilemma ie. what exactly should I get?

To be continued...
 
Re: Walde's L98

Continued...

I'm not into high revving engines and I really like the low RPM torque of the L98. What could I do to increase it even more? And perhaps then some? If rear wheel numbers need to be mentioned anything above 300 hp and 400 lb-ft would be nice. +450 lb-ft would be even nicer. And at as low RPM as possible. I do not see 383" kit in the future. If I would need to rebuild the engine I probably would still keep the stock stroke, just add compression ratio a bit.

I have been looking at AFR heads and at this point I would be ready to go with AFR 180 Street Eliminators #0918. Would this be a good choice or would you recommend something else?

For the heads, what cam should I get? I would prefer a roller camshaft because of the ease of mind compared to flat tappet cam. I could be convinced otherwise, too.

OK, if the heads and cam are set or choices are shortlisted then what about the intake? How stupid would it be to try to run for example those AFR 180s with stock TPI system? How much would I leave hp and tq on the table compared to something like FIRST? I will need to change the throttlebody anyhow so actual cost increase for new system would be X minus 250...350 bucks. FIRST is about $995,-.

So if the difference in power and torque would be considerable then what would you recommend for intake? The Miniram may be wonderful piece of kit but IMHO it would contradict my idea of maximum TQ engine. Or would it?

If we look at USM HSR, Pro Flo XT, FIRST, TPIS big mouth, Edelbrock High Flow, second hand Superram etc. what would you recommend for earlier mentioned heads and cam?

That's basically it - rookie seeking recommendation for heads, cam and intake. Piece of cake. LOL

Yours,
W
 
Re: Walde's L98

well given your goals, of maximizing the low and mid rpm torque curve,
its unfortunate that quality components cost a significant amount of cash, but you can make major improvements in the cars power potential if you use the right matched components, you could very easily boost the power levels by 100-150 or even 200 horse power or more with a carefully selected set of components, the key here is matching the components to the intended application, and not getting confused between matching the cars torque curve to the cars gearing and looking only at the peak hp numbers which may be almost meaningless, if the cars gearing and the engines rpm range don,t match the engine power band and the application
your stock engine produces about 245hp, reaching 400-450hp is no big trick ,because torque is basically derived from the cylinder pressure curve and the force generated, and the larger the displacement , the easier it is to generate increased force on the crank, especially if you raise the intended rpm range OR INCREASE the engines displacement significantly, if you increase compression and, match the head flow and cam timing, it also increases efficiency, in the mid and upper rpm range,resulting,in more efficient cylinder filling and exhaust scavenging efficiency and thus the torque curve,with the correct components, especially if you increase the head flow rates, displacement and compression ratio, that FAST TPI intake design matched to the AFR heads,is a great asset to what your trying to do here.
your engines power potential is mostly the result of effectively burnt fuel/air mixture and cylinder pressure, you can either increase the efficiency and cylinder pressure or increase the rpms thus the number of power strokes per second or both. you will generally find that your going to produce between 1.1 and 1.2 horse power and ft lbs of torque PER CUBIC INCH OF DISPLACEMENT in a well designed combo.

ID strongly suggest GOING with a 383-406 stroker kit,when you select engine components your locking in the rpm band and power potential of an engine to a selected power band, the larger the displacement the more potential torque you can produce because on a small block chevy using common components your looking at between about 1-1.5 ft lbs of torque per cubic inch of displacement.that extra displacement results in a trouble free increase of 50-60 ft lbs.
lets say for an example 1.2 ft lbs per cubic inch, so a larger displacement has a distinct advantage,the cam and intake that are matched to the displacement will have a major effect on the rpm band that torque occurs over.the cams below are designed to maximize the peak torque in the 3300rpm-4000rpm band when matched with the other components listed

as the extra displacement and getting the compression ratio to about 9.0:1-9.4:1 will result in what your trying to do with the parts listed here, keep in mind the combo of the long runner first intake the better flow rates of the AFR heads and those headers will provide a very noticeable boost in the mid rpm range, but having the extra displacement and longer stroke easily adds 40-60 ft lbs over the similar built 350 sbc, over a great deal of the power band

http://ohiocrank.com/chev_sb_shortb.html


the AFR 180cc, or 195cc l98 angle heads, and the

http://www.airflowresearch.com/index.php?cPath=24_25

http://www.airflowresearch.com/index.php?cPath=24_29

FIRST INTAKE
http://www.firstfuelinjection.com/PDRM1966.JPG

and a cam like this crower with 1.6:1 ratio rockers

http://www.crower.com/misc/cam_spec/cam ... 1&x=43&y=5

http://www.summitracing.com/parts/CCA-1602-16/

and those headers you linked to

ID also suggest this oil pan

http://www.cantonracingproducts.com/cgi ... key=15-240

now before you ask, a slightly larger cam with a 218-220/225 230 dur.@ .050 lift on a 112-114 lsa could also be used and produce a bit more horsepower like this, if you go with the 383-406 short block

http://www.lunatipower.com/Product.aspx?id=1988&gid=289

a combo like this will result in enough of an increase in power than you would not need to use first gear very often unless you used racing style tires, theres easily more ft lbs and hp with the stroker than a 350 with that engine built as a 383-406 sbc


read thru these threads


viewtopic.php?f=50&t=1249

viewtopic.php?f=69&t=519

viewtopic.php?f=69&t=1239

http://www.idavette.net/hib/camcon.htm

viewtopic.php?f=69&t=2645
 
Re: Walde's L98

Hey.

Thanks for the reply and suggestions/recommendations.

I have to say that unfortunately any further diving into the engine at this point is strictly a no-no and that is mostly because of budget reasons. The engine is still in good shape but if it had any signs of mechanical problems then it would be another matter. Maybe, just maybe, there's a bigger displacement in the horizon but that would be a year or two away still.

The Dyno 2003 program is surely not accurate tool and IMHO it produces way too high numbers - but I think it can be used to compare different components and their effects on things. I tried that on the Crower cam listed and it and the Crane 114132 made quite similar numbers.

Do you see much difference IF I would choose the AFR 195s instead? Would they be too big for the 350"? On the other hand, if I buy the AFR 180s and then decide to go for 383", would the 180s be too small for that?

I have tried to find feedback of the FIRST intake but not much luck there. Any opinions on the system?

Used Superrams cost the same as new FIRST. Are they that good or are they just overpriced? Which would you personally get?

BR,
W
 
Re: Walde's L98

Walde said:
Hey.

Thanks for the reply and suggestions/recommendations.

I have to say that unfortunately any further diving into the engine at this point is strictly a no-no and that is mostly because of budget reasons. The engine is still in good shape but if it had any signs of mechanical problems then it would be another matter. Maybe, just maybe, there's a bigger displacement in the horizon but that would be a year or two away still.

The Dyno 2003 program is surely not accurate and IMHO it produces way too high numbers - but I think you can use it to compare different components and their effects on things. I tried that Crower cam and the Crane 114132 made quite similar numbers.

thats because the cams are both very similar and designed for the 2500rpm-4500rpm power band

Do you see much difference IF I would choose the AFR 195s instead? Would they be too big for the 350"? On the other hand, if I buy the AFR 180s and then decide to go for 383", would the 180s be too small for that?

theres not a great deal of difference in the expected results between the 180cc and 195cc heads , used on ether engine size as the port cross section and port design are very similar, personally if theres any chance youll go with larger than a 350 displacement Id suggest the 195cc, but again not a big difference, Id expect a difference of about a 200rpm change in the torque peak in the rpm band

I have tried to find feedback of the FIRST intake but not much luck there. Any opinions on the system?

for what your attempting to accomplish. (building a torque monster) ID select the FIRST intake if it was my car, Ive used the superram in the past and its a P.I.T.A. to bolt together and use, in my opinion

Used Superrams cost the same as new FIRST. Are they that good or are they just overpriced? Which would you personally get?

try not to confuse the goal, here, you don,t select the same components if your trying to build an instantly responsive low-mid rpm torque monster, where youll spend most of your time driving at 1800rpm-5000rpm, used for really fun street driving, as you would, if the goal was maximizing the peak horsepower, where youll seldom allow the engine rpms to fall to under 3500-4500rpm, and expect your peak torque to fall closer to 5500rpm and peak hp to fall near 6200rpm-6500rpm

BR,
W
Click to expand...
 
Re: Walde's L98

Cheers.

Thanks for the comments. Information starts to sink slowly in, I think. :lol:

Like you mentioned, as I checked the flow numbers of both 180 and 195 Street Eliminators, both are fairly close to each other. And keep options open in the future then perhaps the 195 would be better to get - I do not see me buying another set ever again so better figure full picture now.

Cams discussed seem to be dual pattern cams usually. Are the single pattern cams in general "obsolete" for today's cylinder heads or what is behind the trend?

Comp Cams Extreme Energy cams, such as XR264, also produce quite nice numbers on "amateur dyno program". Are their ramps too aggressive for a daily driver?

Finally, I contacted FIRST and asked a bunch of questions and an offer. Lets see what they answer.

BR,
W

PS. Will I be loosing much TQ with 1 3/4" primaries vs. 1 5/8"?
 
Re: Walde's L98

Walde said:
Cheers.

Thanks for the comments. Information starts to sink slowly in, I think. :lol:

Like you mentioned, as I checked the flow numbers of both 180 and 195 Street Eliminators, both are fairly close to each other. And keep options open in the future then perhaps the 195 would be better to get - I do not see me buying another set ever again so better figure full picture now.

Cams discussed seem to be dual pattern cams usually. Are the single pattern cams in general "obsolete" for today's cylinder heads or what is behind the trend?

read thru this link and its sub links
viewtopic.php?f=52&t=3123&p=8329&hilit=isky#p8329

Comp Cams Extreme Energy cams, such as XR264, also produce quite nice numbers on "amateur dyno program". Are their ramps too aggressive for a daily driver?

personally I don,t suggest use of comp cams, they make a decent cam but their tech support is a bad joke, and Ive had durability issues, in the past
heres that comp cam
http://www.compcams.com/Company/CC/cam- ... d=157&sb=2


ID go this route, with the 1.6:1 roller lifters

http://www.crower.com/misc/cam_spec/cam ... 1&x=43&y=5


Finally, I contacted FIRST and asked a bunch of questions and an offer. Lets see what they answer.

BR,
W

PS. Will I be loosing much TQ with 1 3/4" primaries vs. 1 5/8"?
Click to expand...

not that youll notice unless your on a dyno, and how much wheel spin do you really want? will leaving 45 feet of dark black marks on the pavement from a hard launch totally ruin your day ,if you know that it might have been 47 feet with different headers?
and Ive got to point out youll gain more mid-upper rpm power as a trade off with the larger primaries, making the car faster
but keep in mind that headers lose efficiency, very quickly unless the exhaust system they are connected to is very free flow and non-restrictive

viewtopic.php?f=56&t=3155

viewtopic.php?f=56&t=495

viewtopic.php?f=56&t=1303

viewtopic.php?f=56&t=3529
 
Re: Walde's L98

Hey.

Actually I'd prefer not to leave black marks at all as that's not what I'm after.

My question about primary sizes was merely from the viewpoint that I did not know if the 1 3/4" on a 350 is "too big" resulting in hole in the TQ curve etc. I have never built a car engine before, just a 124" TC HD and with Harleys the hole seemed to appear quite frequently on different dynos depending on exhaust sizing and related parts. Not on mine, though. :D

Thanks for the links. Lots of reading to do. :mrgreen:

It starts to sink slowly that there just is no one specific Magic Cam on the market as all those, for example 2500-4500 rpm power band cams, just go circles around the same thing and there just is not much to play with, few degrees here and there, a bit of lift here and there. Which on the other hand is not that bad for the customer.
 
Re: Walde's L98

"It starts to sink slowly that there just is no one specific Magic Cam on the market as all those, for example 2500-4500 rpm power band cams, just go circles around the same thing and there just is not much to play with, few degrees here and there, a bit of lift here and there. Which on the other hand is not that bad for the customer."

its the total combo of MATCHED components selected,and how there inter-act with each other and not any single component that will allow your engine to produce good hp, in the rpm band your designing the combo for.
now if you start MIS-MATCHING components your going to be limited by the weakest link in the combo chain
 
Re: Walde's L98

Cheers.

I'm getting increasingly and utterly frustrated with trying to communicate with companies such as TPIS and even Melrose. Melrose did answer my exhaust questions and let me know prices but when it came to ordering the set I reckon they have closed the shop down for good. :cry:

I need plan B ie. set of headers which are widely available at distributors:

Do you have experience of Hedman's 68448? They are supposed to be long tubes with 1 5/8" primaries, no AIR or EGR, thermal coating etc. Any idea if they are worth the under $600,- they seem to cost?
 
Re: Walde's L98

Lot's of reading but as the topic is interesting then it's educating.

FWIW, Melrose woke up after another e-mail and they realised I'm a customer trying to place an order and now we are getting forward. :idea:

Not engine related - well, in a way:

I'm making a list of ball joints etc. to rebuild the suspension. I have a "clunk" in the driveline an apart from changing all U-joints I figured I'd change the motor mounts too while working with the headers etc. Also, I will order an Energy Suspension Master Kit.

Energy Suspension don't seem to make motor mounts for -86 Corvette. Any suggestions for a brand to get?
 
Re: Walde's L98

most chevy first gen v8 motor mounts, on both the sbc and bbc engines come in one of two sizes, youll want to measure the mounts your replacing and order POLY motor mounts that are similar, because they could be ether type in most applications



mount2.jpg



early style "short and wide" motor mount that measures 2 5/8 in. between the ears and 1 3/4 in. tall to the center of the through bolt hole
http://www.summitracing.com/parts/ENS-3-1120G/




mount1.jpg

early style "tall and narrow" motor mount that measures 2 3/8 in. between the ears and 2 3/16 in. tall to the center of the through bolt hole

http://www.summitracing.com/parts/ENS-3-1122G/

mount3.jpg

mount4.jpg

mount5.jpg

your 1986 mounts may look like either of these two styles
http://www.ecklers.com/corvette-motor-m ... -1991.html

http://www.napaonline.com/Search/Detail ... 12+2012030
 
Re: Walde's L98

I've been following this post, If you can change motor mounts and put headers in, then you can stroke the engine, go with the 383 then port and polish YOUR heads, with 3 angle valve job. Although the stock heads and intake Max out at around 400hp , thats without port work and a chip retune. I would also drop in a set of large tube runners to aid in feeding the larger displacement. Also it will keep your L-98 STOCK Looking to the untrained eye. Keep your cam selection Mild. Your not building an F-1 high rpm screamer so make sure your parts work in HARMONY. I personally recommend the Bosch 3rd gen injectors, night and day difference from those Multecs if you still have them, again common mistake is to get injector flow rates that exceed your engine's requirements. Exhaust sounds like your on the correct path, just ask grumpy when we hollowed out my clogged cat...Weight reduction is another issue I havent made a post about that I will do soon. Lose the frisbee, spare tire, AIR Pump, Get aftermarket Rims, Lose the A/C (If you Can)..ETC. Another issue here could be a rear gear change and an aftermarket torque converter, Aluminum flywheel. As far as suspension, Dont go with Poly if you want the car to have that "LIKE NEW" ride, Poly's are durable and hold suspension geometry better but are noisy and less shock absorbing than the stock rubber or composite bushings. Composite springs further reduce weight and add to performance but are pricey. I'm rambling now, I just wanted to join the conversation, it really boils down to how much you can afford.. ;)
 
Re: Walde's L98

Thanks Grumpy.

There's a discussion on CF and they are saying that

On CF they said:
Energy Suspension part number 3.1127G fits the "2713" clamshell. Energy Suspension lists it as a 93-97 Camaro left-side motor mount insert.

the 2713 is the replacement motor mount for my 91 L98, both sides. Anchor Industries 2713.
Click to expand...

Said ES 3.1127G looks like this
ES31116_lg.gif


Perhaps that would fit?

Those Ecklers parts are just 10 bucks a piece so might get both, just in case.
 
Re: Walde's L98

Doodad, cheers mate.

I hear you and I do agree with your and Grumpy's suggestions of stroker kit. Unfortunately, at this point it will not happen, as there are for the moment severe budgetary limitations which cause me to consider each move thoroughly and at the same pick the parts also so that they will work in the future with possible bigger displacement. On the other hand a 350 cid 300 hp C4 GT cruiser would do just fine.

Right now it seems that even heads, roller cam kit and intake are out of reach this winter meaning that freeing each horse, that can be freed with headers and deleting of AIR, EGR and cats, will be done but that's about it. Maybe more in the future, we'll see.
 
Re: Walde's L98

Hollow Cats will help a lot, EGR will really do nothing and can throw codes on long trips, but you can put a resistor in the harness if it becomes a problem, or tune it out. The Air pump is pretty much a free spinning pulley, so there is not a lot of parasitic drag involved here, but there is weight savings, and it really just looks better to clean up the engine compartment, spark plug changes become easier also. Stick with intake/exhaust for now, and weight reduction, new tune and a tune up, and you'll be close to your immediate goals. Keep me posted.Cheers
 
Re: Walde's L98

everything looks GREAT! I,m sure youll be pleased once its installed , just remember to use STAINLESS low restriction 3" mufflers, so as not to restrict flow and reduce the exhaust systems potential
 
Re: Walde's L98

That exhaust system is so pretty, I would have to call that ART!!!

Let us know how well it works out for you!
 
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