Hello,
I am wanting to build a 350CI Gen1 Small Block Chevy for my 260Z SCCA car. Now I have been through the rule book and realize that this engine will put me in a totally different class where I will have to spend a lot of time and money to ever be competitive. However, after reading some things this seems to be a swap that a lot of people do. My plan is to build the engine and mate it to a built t-5 transmission. I am a college student, so this is something I am trying to do on a low budget per the winter. Honestly, I know that I am going to be investing some money in this project so I am prepared for that aspect of things, I just don't want it to get out of control.
As for the engine I already have the four bolt main block. As I previously stated my goal is to build this engine for SCCA as the 260 is my SCCA car. In my mind I'm wanting to do a DZ302 homage with the 350. I am already looking into a cross ram setup, and as my primary goal is autocross and club racing, I am wanting something that makes power in the high rpm range. However, I also want to be able to drive the car to the events so running on 93 octane is a must. I have purchased several books (How to hotrod your small block, how to rebuild a small block, smokey yunick's power secrets, etc.) and have been reading them to familiarize myself with this project.
As I previously stated I already have a block and a forged crank. I have been looking at some heads and that's where my questions come in. The heads I'm looking at are aluminum (to keep weight down) and made by Procomp. Now I know that I'm going to get some crap for going with the cheap pro comp heads. I've done a ton of reading on them and read that some people hate them and others like them. Is it the cheap route? Yes. However, I have talked to a (fairly) local guy who does head work and he assures me that he has worked on pro comps before and can get some pretty good flow numbers out of them. I have checked with some references and I do trust his word. That said, I am lost on intake runner size. Pro comp offers them in 190, 200, and 210 sizes. I have already settled on getting the angled plugs over the straight. I'm just needing to know what intake runner size is best for my build. Hoping someone here can help me out.
Thanks,
Han
ok, first some experience in building similar engines might help, so let me assure you that after building a good many 302-327-350 displacement , street/strip, performance engines and having looked over a few of those cheap import heads heres what ID suggest,keep in mind this hobby,s never cheap, but you don,t have to have the latest and most expensive parts to have a nice combo that puts out decent power, assuming your building a 350 for high rpm use on a limited budget.
keeping in mind both a limited budget and wanting decent power, I,D SUGGEST you get the quench distance in the .040-.044 range, Id suggest erson 1.6 roller rocker and a rocker stud girdle with tall valve covers
id strongly suggest a 7-8 quart baffled oil pan
an engine combo like im describing here won,t be ideal for any car that is geared to cruise at highway speeds with the engine spinning less than 3200rpm
and your very likely to NEED a trans fluid cooler if its an auto transmission.
USE THE CALCULATORS to match port size to intended rpm levels... but keep in mind valve lift and port flow limitations
http://www.wallaceracing.com/runnertorquecalc.php
http://www.wallaceracing.com/ca-calc.php
http://www.wallaceracing.com/area-under-curve.php
http://www.wallaceracing.com/chokepoint.php
http://www.wallaceracing.com/header_length.php
Id do the calculations required to select pistons , matching the heads you select that get you in the 10.3-10.5:1 compression range with the heads selected
do a mild port bowl clean-up on the heads, and get springs that allow a .600 minimal lift with about a 120-130lb seat load and 320-340lb open load rate, for a flat tappet solid lifter cam.
set ring gaps at about .0045 per inch of bore diam.
[/color]
HERES THE ROUTE ID TAKE ON A BUDGET
HEADS (195cc versions)
http://www.profilerperformance.com/raci ... -23-degree
crane solid lifter 110921 cam
http://www.summitracing.com/parts/crn-110921
HAS A VERY OBVIOUS LOPEY IDLE AND WON,T IDLE WELL BELOW ABOUT 900RPM
but it also tends to have a very impresive and responsive power band in the 3500rpm-6500rpm range in an engine with properly matched parts, it not ideal for high way cruising but great for blasting out of track curves onto long straits, if you spend 90% of your track time between 3500rpm and 6500rpm youll love it!
lifters
http://www.summitracing.com/parts/cca-800-16
intake
http://www.summitracing.com/parts/hly-300-110
carb
http://www.summitracing.com/parts/hly-0-80531
rods
http://www.summitracing.com/parts/sca-26000716
find or fabricate headers with a 1.3/4" primary tube length near 38"-39" long with a 18"-20" long 3"-3.5" diam collector
if you can,t find the longer headers and have some skill with a welder cutting off the factory collector and adding these longer header collector extensions usually help noticeably, a combo like this is going to produce decent power in the 3500rpm-6500rpm band but not be ideal for long distance cruising at less than 2500rpm or great on gas mileage as its mostly designed to run hard in the 3500rpm-6500rpm power range
http://www.summitracing.com/parts/FLO-C134218234/
Id suggest clevite (H) series bearings and 6" SCAT connecting rods with 7/16" ARP rod bolts
IF I HAD a BIT MORE CASH I,D GO WITH THE 210CC heads, get the compression ratio up near 10.8:1 and use a SOLID ROLLER CAM LIKE THIS
http://www.race-mart.com/Crane_Cams-416776.html
HERES A FEW RELATED BUILD THREADS
http://www.superchevy.com/technical/eng ... ine_build/
keep in mind its the total combo NOT just the port and runner size alone,
within reasonable limits ,intake port size is one of the least important factors.
your dealing with factors that are interdependent, each change effects the way the other factors respond and interact,
there are ways to predict trends or compensate for changes
change the cam LSA
,duration and lift
engines compression ratio,
intake runner length
header primary diameter and length
and you could very easily find the larger ports made significantly better power.
ID much rather, be faced with a combo where I compensate for a cylinder head with a port size that might be a bit larger than ideal for the application than one thats a bit restrictive to flow, simply because a restrictive port limits upper rpm and peak power far more than a larger port tends to loose low speed responsiveness, because that is much easier to compensate for with changes to the intake, or cam timing or compression, header design etc.
USE THE CALCULATORS, YOULL, QUICKLY FIND THE LIMITATIONS
http://www.rbracing-rsr.com/runnertorquecalc.html
http://www.wallaceracing.com/chokepoint.php
http://www.wallaceracing.com/header_length.php
http://garage.grumpysperformance.co...ing-parts-and-a-logical-plan.7722/#post-49738
http://garage.grumpysperformance.com/index.php?threads/port-speeds-and-area.333/
http://garage.grumpysperformance.co...-the-charts-calculators-and-basic-math.10705/
http://garage.grumpysperformance.com/index.php?threads/carb-intake-test.58/
http://garage.grumpysperformance.co...lsa-effects-your-compression-torque-dcr.1070/
http://garage.grumpysperformance.com/index.php?threads/porting-can-help.462/
http://garage.grumpysperformance.com/index.php?threads/valve-seat-angles-and-air-flow.8460/
http://garage.grumpysperformance.com/index.php?threads/is-backpressure-hurting-your-combo.495/
http://www.hotrod.com/how-to/engine/ccrp-1209-eight-budget-sbc-head-shootout/
http://garage.grumpysperformance.co...spacers-and-related-intake-modification.1038/
http://garage.grumpysperformance.com/index.php?threads/sellecting-cylinder-heads.796/
http://garage.grumpysperformance.co...mbers-or-a-good-street-combo-your-after.5078/
I am wanting to build a 350CI Gen1 Small Block Chevy for my 260Z SCCA car. Now I have been through the rule book and realize that this engine will put me in a totally different class where I will have to spend a lot of time and money to ever be competitive. However, after reading some things this seems to be a swap that a lot of people do. My plan is to build the engine and mate it to a built t-5 transmission. I am a college student, so this is something I am trying to do on a low budget per the winter. Honestly, I know that I am going to be investing some money in this project so I am prepared for that aspect of things, I just don't want it to get out of control.
As for the engine I already have the four bolt main block. As I previously stated my goal is to build this engine for SCCA as the 260 is my SCCA car. In my mind I'm wanting to do a DZ302 homage with the 350. I am already looking into a cross ram setup, and as my primary goal is autocross and club racing, I am wanting something that makes power in the high rpm range. However, I also want to be able to drive the car to the events so running on 93 octane is a must. I have purchased several books (How to hotrod your small block, how to rebuild a small block, smokey yunick's power secrets, etc.) and have been reading them to familiarize myself with this project.
As I previously stated I already have a block and a forged crank. I have been looking at some heads and that's where my questions come in. The heads I'm looking at are aluminum (to keep weight down) and made by Procomp. Now I know that I'm going to get some crap for going with the cheap pro comp heads. I've done a ton of reading on them and read that some people hate them and others like them. Is it the cheap route? Yes. However, I have talked to a (fairly) local guy who does head work and he assures me that he has worked on pro comps before and can get some pretty good flow numbers out of them. I have checked with some references and I do trust his word. That said, I am lost on intake runner size. Pro comp offers them in 190, 200, and 210 sizes. I have already settled on getting the angled plugs over the straight. I'm just needing to know what intake runner size is best for my build. Hoping someone here can help me out.
Thanks,
Han
ok, first some experience in building similar engines might help, so let me assure you that after building a good many 302-327-350 displacement , street/strip, performance engines and having looked over a few of those cheap import heads heres what ID suggest,keep in mind this hobby,s never cheap, but you don,t have to have the latest and most expensive parts to have a nice combo that puts out decent power, assuming your building a 350 for high rpm use on a limited budget.
keeping in mind both a limited budget and wanting decent power, I,D SUGGEST you get the quench distance in the .040-.044 range, Id suggest erson 1.6 roller rocker and a rocker stud girdle with tall valve covers
id strongly suggest a 7-8 quart baffled oil pan
an engine combo like im describing here won,t be ideal for any car that is geared to cruise at highway speeds with the engine spinning less than 3200rpm
and your very likely to NEED a trans fluid cooler if its an auto transmission.
USE THE CALCULATORS to match port size to intended rpm levels... but keep in mind valve lift and port flow limitations
http://www.wallaceracing.com/runnertorquecalc.php
http://www.wallaceracing.com/ca-calc.php
http://www.wallaceracing.com/area-under-curve.php
http://www.wallaceracing.com/chokepoint.php
http://www.wallaceracing.com/header_length.php
Id do the calculations required to select pistons , matching the heads you select that get you in the 10.3-10.5:1 compression range with the heads selected
do a mild port bowl clean-up on the heads, and get springs that allow a .600 minimal lift with about a 120-130lb seat load and 320-340lb open load rate, for a flat tappet solid lifter cam.
set ring gaps at about .0045 per inch of bore diam.
[/color]
HERES THE ROUTE ID TAKE ON A BUDGET
HEADS (195cc versions)
http://www.profilerperformance.com/raci ... -23-degree
crane solid lifter 110921 cam
http://www.summitracing.com/parts/crn-110921
HAS A VERY OBVIOUS LOPEY IDLE AND WON,T IDLE WELL BELOW ABOUT 900RPM
but it also tends to have a very impresive and responsive power band in the 3500rpm-6500rpm range in an engine with properly matched parts, it not ideal for high way cruising but great for blasting out of track curves onto long straits, if you spend 90% of your track time between 3500rpm and 6500rpm youll love it!
lifters
http://www.summitracing.com/parts/cca-800-16
intake
http://www.summitracing.com/parts/hly-300-110
carb
http://www.summitracing.com/parts/hly-0-80531
rods
http://www.summitracing.com/parts/sca-26000716
find or fabricate headers with a 1.3/4" primary tube length near 38"-39" long with a 18"-20" long 3"-3.5" diam collector
if you can,t find the longer headers and have some skill with a welder cutting off the factory collector and adding these longer header collector extensions usually help noticeably, a combo like this is going to produce decent power in the 3500rpm-6500rpm band but not be ideal for long distance cruising at less than 2500rpm or great on gas mileage as its mostly designed to run hard in the 3500rpm-6500rpm power range
http://www.summitracing.com/parts/FLO-C134218234/
Id suggest clevite (H) series bearings and 6" SCAT connecting rods with 7/16" ARP rod bolts
IF I HAD a BIT MORE CASH I,D GO WITH THE 210CC heads, get the compression ratio up near 10.8:1 and use a SOLID ROLLER CAM LIKE THIS
http://www.race-mart.com/Crane_Cams-416776.html
HERES A FEW RELATED BUILD THREADS
http://www.superchevy.com/technical/eng ... ine_build/
keep in mind its the total combo NOT just the port and runner size alone,
within reasonable limits ,intake port size is one of the least important factors.
your dealing with factors that are interdependent, each change effects the way the other factors respond and interact,
there are ways to predict trends or compensate for changes
change the cam LSA
,duration and lift
engines compression ratio,
intake runner length
header primary diameter and length
and you could very easily find the larger ports made significantly better power.
ID much rather, be faced with a combo where I compensate for a cylinder head with a port size that might be a bit larger than ideal for the application than one thats a bit restrictive to flow, simply because a restrictive port limits upper rpm and peak power far more than a larger port tends to loose low speed responsiveness, because that is much easier to compensate for with changes to the intake, or cam timing or compression, header design etc.
USE THE CALCULATORS, YOULL, QUICKLY FIND THE LIMITATIONS
http://www.rbracing-rsr.com/runnertorquecalc.html
http://www.wallaceracing.com/chokepoint.php
http://www.wallaceracing.com/header_length.php
http://garage.grumpysperformance.co...ing-parts-and-a-logical-plan.7722/#post-49738
http://garage.grumpysperformance.com/index.php?threads/port-speeds-and-area.333/
http://garage.grumpysperformance.co...-the-charts-calculators-and-basic-math.10705/
http://garage.grumpysperformance.com/index.php?threads/carb-intake-test.58/
http://garage.grumpysperformance.co...lsa-effects-your-compression-torque-dcr.1070/
http://garage.grumpysperformance.com/index.php?threads/porting-can-help.462/
http://garage.grumpysperformance.com/index.php?threads/valve-seat-angles-and-air-flow.8460/
http://garage.grumpysperformance.com/index.php?threads/is-backpressure-hurting-your-combo.495/
http://www.hotrod.com/how-to/engine/ccrp-1209-eight-budget-sbc-head-shootout/
http://garage.grumpysperformance.co...spacers-and-related-intake-modification.1038/
http://garage.grumpysperformance.com/index.php?threads/sellecting-cylinder-heads.796/
http://garage.grumpysperformance.co...mbers-or-a-good-street-combo-your-after.5078/
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