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why do you like .028? Curious is all
Im understanding what your saying about getting foundation!!!!! We have 5 other heads on project, stuff gets twisted easy I’m seeing.... then we have teachers that throw out the this motor will never hold up to 1000hp without forged internals (old school guys) and 90% of the group wants to prove them wrong.
ill find out more about this trans next week
for the throttle body the said they had a 90 mm 4 bolt already- we Will see (haven’t seen it yet)
28 is what my "go to" guys said. so we did it and its working.Originally Posted by trxmxzx
why do you like .028? Curious is all
Im understanding what your saying about getting foundation!!!!! We have 5 other heads on project, stuff gets twisted easy I’m seeing.... then we have teachers that throw out the this motor will never hold up to 1000hp without forged internals (old school guys) and 90% of the group wants to prove them wrong.
ill find out more about this trans next week
for the throttle body the said they had a 90 mm 4 bolt already- we Will see (haven’t seen it yet)
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Originally Posted by Choda
28 is what my "go to" guys said. so we did it and its working.
perfect- good to know
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they are still trying to figure on a turbo- teacher is cool with a smaller one if cheap (like the link posted) tech wants a 88mm borg - is hard to tell them what’s budget
i had other projects to do but I heard they are talking water to air inter cooler .... at that point I stayed out of conversation
ill update this when more parts come in as they “budget” build this lol
Sounds like a real clusterfuck of ideas. The teacher needs to get these guys in line with GOALS, not throwing something together with big-this, expensive-that to see what it will do.Originally Posted by trxmxzx
they are still trying to figure on a turbo- teacher is cool with a smaller one if cheap (like the link posted) tech wants a 88mm borg - is hard to tell them what’s budget
i had other projects to do but I heard they are talking water to air inter cooler .... at that point I stayed out of conversation
ill update this when more parts come in as they “budget” build this lol
1. How fast do you want to go?
https://robrobinette.com/et.htm?weig...x=0&submit.y=0
Set goals for power to weight ratio based on where it can get you on this hypothetical calculator.
2. Now that you have a power goal in mind based on a rough estimate of weight, how much airflow do you need to make that?
https://www.gregraven.org/hotwater/c...ors/airflow-hp
Enter your desired HP goal to get an estimate of how much air volume/pressure you'll need a compressor to push to get you there. This will give you a ballpark.
3. Figure out the finer points.
This method and formulas was taken from A. Graham Bell's book, 'Forced Induction Performance Tuning'.
First we need to calculate the engine air flow rate (CFM). The formula for this is:
CFM = L x RPM x VE x Pr / 5660
Where L = engine capacity in liters
RPM = maximum engine speed (adjustable based on limiter settings)
VE = engine volumetric efficiency. (I'd guess around 85% for a 2V LS)
Pr = pressure ratio
To calculate the pressure ratio you need to know what boost pressure you want to run and then plug that into the following formula:
Pr = 14.7 + Boost / 14.7 (Typically, you'll want to run richer than stoich for safety purposes, so a lower number than 14.7 is more realistic. A lot of guys run in the 12.5 range under boost.)
More info here.
Quote:
1. How fast do you want to go?
https://robrobinette.com/et.htm?weig...x=0&submit.y=0
Set goals for power to weight ratio based on where it can get you on this hypothetical calculator.
2. Now that you have a power goal in mind based on a rough estimate of weight, how much airflow do you need to make that?
https://www.gregraven.org/hotwater/c...ors/airflow-hp
Enter your desired HP goal to get an estimate of how much air volume/pressure you'll need a compressor to push to get you there. This will give you a ballpark.
3. Figure out the finer points.
This method and formulas was taken from A. Graham Bell's book, 'Forced Induction Performance Tuning'.
First we need to calculate the engine air flow rate (CFM). The formula for this is:
CFM = L x RPM x VE x Pr / 5660
Where L = engine capacity in liters
RPM = maximum engine speed (adjustable based on limiter settings)
VE = engine volumetric efficiency. (I'd guess around 85% for a 2V LS)
Pr = pressure ratio
To calculate the pressure ratio you need to know what boost pressure you want to run and then plug that into the following formula:
Pr = 14.7 + Boost / 14.7 (Typically, you'll want to run richer than stoich for safety purposes, so a lower number than 14.7 is more realistic. A lot of guys run in the 12.5 range under boost.)
More info here.
thank you this is some good info!!! Originally Posted by BudRacing
Sounds like a real clusterfuck of ideas. The teacher needs to get these guys in line with GOALS, not throwing something together with big-this, expensive-that to see what it will do.1. How fast do you want to go?
https://robrobinette.com/et.htm?weig...x=0&submit.y=0
Set goals for power to weight ratio based on where it can get you on this hypothetical calculator.
2. Now that you have a power goal in mind based on a rough estimate of weight, how much airflow do you need to make that?
https://www.gregraven.org/hotwater/c...ors/airflow-hp
Enter your desired HP goal to get an estimate of how much air volume/pressure you'll need a compressor to push to get you there. This will give you a ballpark.
3. Figure out the finer points.
This method and formulas was taken from A. Graham Bell's book, 'Forced Induction Performance Tuning'.
First we need to calculate the engine air flow rate (CFM). The formula for this is:
CFM = L x RPM x VE x Pr / 5660
Where L = engine capacity in liters
RPM = maximum engine speed (adjustable based on limiter settings)
VE = engine volumetric efficiency. (I'd guess around 85% for a 2V LS)
Pr = pressure ratio
To calculate the pressure ratio you need to know what boost pressure you want to run and then plug that into the following formula:
Pr = 14.7 + Boost / 14.7 (Typically, you'll want to run richer than stoich for safety purposes, so a lower number than 14.7 is more realistic. A lot of guys run in the 12.5 range under boost.)
More info here.
^^^ yup. way to many ideas, which is why i said hammer down the fundamentals first to get the car running.
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well game changer- teacher just traded another school a engine Dyno for a brand new LS7- Originally Posted by Choda
^^^ yup. way to many ideas, which is why i said hammer down the fundamentals first to get the car running.
i have no clue which way this will go now- with the tables above if the car weighed in at 3200lbs (which it’s gutted, so probably less) at 500 wheel will be 10.5 but 600 wheel will be 9.96
So a little update: the motor they got was not a ls7 it was a newer LT1 6.2 DI
so continuing on with the 5.3 build- we pulled pistons last night to open up those rings some. I was surprised on how tight the top rings are - top .013 second .025 and oil was .018
i wanted top .024 and second .026
i got over ruled by tech and put top ring at .0265 and second at .027
he said gap it @ .007 per inch of bore
so on another note the 5.3 has these 243 heads which puts the cpr at 9.9:1 if I’m correct wonder if we should throw some 317 on there to lower it to around 9:1 to reduce the chance of detonation seeing this is a learning car for the school and students and teachers will be tuning it
plus I conveniently have a set of 317 in my garage I’d trade for those 243’s
so continuing on with the 5.3 build- we pulled pistons last night to open up those rings some. I was surprised on how tight the top rings are - top .013 second .025 and oil was .018
i wanted top .024 and second .026
i got over ruled by tech and put top ring at .0265 and second at .027
he said gap it @ .007 per inch of bore
so on another note the 5.3 has these 243 heads which puts the cpr at 9.9:1 if I’m correct wonder if we should throw some 317 on there to lower it to around 9:1 to reduce the chance of detonation seeing this is a learning car for the school and students and teachers will be tuning it
plus I conveniently have a set of 317 in my garage I’d trade for those 243’s
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Quote:
plus I conveniently have a set of 317 in my garage I’d trade for those 243’s
In that case, I'd definitely suggest that. Originally Posted by trxmxzx
plus I conveniently have a set of 317 in my garage I’d trade for those 243’s
Otherwise, I'd leave it alone and move forward with the build.
Quote:
Otherwise, I'd leave it alone and move forward with the build.
Originally Posted by BudRacing
In that case, I'd definitely suggest that. Otherwise, I'd leave it alone and move forward with the build.
lol right I have a lq9 just hanging out, thought damn i could make a iron ls2
with that ring gap so tight makes me wonder about my 04 5.3 (thought they were around .016-.018 stock) that I’m throwing 8 lbs at and wanting more
swathdiver
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Mar 28, 2026
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The 2007-2009 LC9s Compression Ratio is 9.95:1. It was lowered to 9.6:1 when they changed pistons in 2010.
The exhaust valves are larger on the 243 heads, I'd keep them. Those knuckleheads are going to blow it up anyway.
The exhaust valves are larger on the 243 heads, I'd keep them. Those knuckleheads are going to blow it up anyway.