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Old 10-07-2012, 04:39 PM
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how much timing at idle for this cam?

234 / 244 .488" / .510" on 112 lsa

this is the edelbrock rpm performer cam

my old 224 summit cam i had 24* at idle and it ran fine i swapped out the summit cam for the edelbrock cam i originally had in the engine

at 24* the edelbrock cam is lazy so i put it upto 32* and its better but maybe just a touch lazy when first opening the throttle


this is a fuel injected twin turbo engine
9.2-1 cr


what would u guys say this cam would need for ignition timing at idle
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Old 10-07-2012, 04:42 PM
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32 may be a bit too much, I would guess 28-30 degrees at idle, and 32-34 degrees total.
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Old 10-07-2012, 04:46 PM
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Quote:
Originally Posted by ap72 View Post
32 may be a bit too much, I would guess 28-30 degrees at idle, and 32-34 degrees total.
hmmm i never thought about the possibility of 32* at idle being to much , i will set it to 28-30* at idle and see if it picks up a lil bit.

other then that i pretty much have timing all in by 3k to start
from 1psi to 12 psi im at 25* total and from 13psi to 19 psi im at 22*total above 19 psi im down to 19/20*

under non boost conditions im all in at 3k with 34*

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Old 10-07-2012, 04:50 PM
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your off idle response will be a hair sluggish with correct timing. You'll have some off idle reversion to work around- hence larger cams are paired with higher stalls.
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Old 10-07-2012, 05:06 PM
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thanks converter is a touch to tight, i had a 4l80 in the car with a manual valve body and trans brake and a 3,200 stall converter but second gear started slipping so i pulled it out and reinstalled a stock 700r4 and 2,200 stall converter for now .

cam is slightly oversized for this setup but i knew that when i put it back in, i was willing to trade off some power for a nice grumpy idle
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Old 10-07-2012, 05:13 PM
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Quote:
Originally Posted by Project89 View Post
thanks converter is a touch to tight, i had a 4l80 in the car with a manual valve body and trans brake and a 3,200 stall converter but second gear started slipping so i pulled it out and reinstalled a stock 700r4 and 2,200 stall converter for now .

cam is slightly oversized for this setup but i knew that when i put it back in, i was willing to trade off some power for a nice grumpy idle
a grumpy idle and turbos... You know that usually doesnt mix well, unless you have larger than normal exhaust housings and a good header, even then its usually race only as it leads to reversion issues.
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Old 10-07-2012, 05:16 PM
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You can lock out the timng and run 36deg BTDC, Then use a boost retard box to retard the timing
as boost comes in.
The cam is not a good "turbo cam" A single pattern 224-224 n 114 is better.
or a 234 intake 224 exhaust @.050" cam on 114+LSA .. with 234 duration the boost will start late.

I would reinstall the 224-224 114 LSA cam but degree it in and install straight up in 114-114 centers.
Instead of advanced. It will have the top end power you wanted and build turbo boost.

Too much overlap and exhaust duration on the closing side allows the turbo boost to go right thru the motor.
Its easy to over cam a turbo motor.
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Old 10-07-2012, 05:18 PM
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Quote:
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a grumpy idle and turbos... You know that usually doesnt mix well, unless you have larger than normal exhaust housings and a good header, even then its usually race only as it leads to reversion issues.
yeah im well aware of it i just could stand the stock like idle of the summit 224 cam any more, the edelbrock came in the engine that wa sin the car when i bought it . so i figured id stick it back in and give it a go and see if its really that bad.

few guys on ttf.com have been able to run some pretty wild tight lsa cams without very many issues so i figure this cam being a good bit tamer might actually just work out pretty good. if not i have the option to reinstall the summit 224 or maybe even try out the sum 234/234
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Old 10-07-2012, 05:22 PM
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you really need to get your self a "turbo cam"
Wide LSA with less ex duration say 280/230-480" intake 268/222 ..464" exhaust exhaust 115 lsa.
Basicly a turbo cam version of the comp 280 magnum cam.

the 234-244 112 cam is a roots supercharger cam.
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Old 10-07-2012, 05:22 PM
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Quote:
Originally Posted by Project89 View Post
yeah im well aware of it i just could stand the stock like idle of the summit 224 cam any more, the edelbrock came in the engine that wa sin the car when i bought it . so i figured id stick it back in and give it a go and see if its really that bad.

few guys on ttf.com have been able to run some pretty wild tight lsa cams without very many issues so i figure this cam being a good bit tamer might actually just work out pretty good. if not i have the option to reinstall the summit 224 or maybe even try out the sum 234/234
Going bigger on the am will not help things, nor will a reverse split.

To run a bigger cam using the parts you have first start with a good turbo header system, and then look into increasing the exhaust housing size. With more overlap exhaust reversion becomes a huge issue a well built header and proper exhaust housing size can greatly eliminate a lot of that.
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Old 10-07-2012, 05:41 PM
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Quote:
Originally Posted by F-BIRD'88 View Post
you really need to get your self a "turbo cam"
Wide LSA with less ex duration say 280/230-480" intake 268/222 ..464" exhaust exhaust 115 lsa.
Basicly a turbo cam version of the comp 280 magnum cam.

the 234-244 112 cam is a roots supercharger cam.
from previous twin turbo builds with the tpi intake, the best cams for power would be the summit 224/224 or the comp 268, both of these cams have pushed tpi toped turbo engines well into the 9's and just into the 8's


i know what would be ideal for this motor, and that summit 224 cam was awsome but like i said im willing to trade off some power for sound, i wont be racing the car enough to worry about squeezing every last bit of hp out of it

on a build with small valve truck heads and only a port matched tpi intake on a .40 over 350 that cam (224/224) made almost 700rwhp on 23psi from twin gn turbos. way more then i really need, i could literally give up 100-150 hp and not really care as long as driveability dosent suffer a whole lot


power numbers arent as important to me at the moment, more along the lines of if it will drive ok with the cam

this engine is an experiment for me as ive never had to tune anything at the altitude i am at 6,500ft above seal level. compared to being 0-200ft below is what im used to.

once im comfortable the altitude wont give me any headaches tuning i will be building an 227 afr headed 434 sb , with a single plane efi manfold for the real engine , paired with a set of gt3582r's or a pair of p trimed 66mm turbos

on this engine having everything perfectly matched will be much more of a priority
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Old 10-07-2012, 05:48 PM
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well the TPI intake and big cams is a mismatch. The intake tuned runners some 24" total tune to a low
rpm and are too small for high air flow. (power)
Get a short runner or siamese the TPI. Same with restrictive truck heads with small valves.
A big cam is a mismatch.
Turbo cams do not have a street machine idle.

You could be making a lot more power with less boost. Most of your gauge boost is pure head and intake passage restriction.
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Old 10-07-2012, 06:14 PM
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Quote:
Originally Posted by F-BIRD'88 View Post
well the TPI intake and big cams is a mismatch. The intake tuned runners some 24" total tune to a low
rpm and are too small for high air flow. (power)
Get a short runner or siamese the TPI. Same with restrictive truck heads with small valves.
A big cam is a mismatch.
Turbo cams do not have a street machine idle.

You could be making a lot more power with less boost. Most of your gauge boost is pure head and intake passage restriction.

i do have a semi converted lt1 intake, i need to finish the welding on it to use it, that intake would deff be better but has its own airflow issues


im not using small valve truck heads on mine though the 882's arent much better they are atleast better, the head shave been cleaned up , and the tpi is ported but im not going to drop 400 bucks on a set of runners to siamess them
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Old 10-07-2012, 06:48 PM
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get rid of the heads. You are not going to make any power with them. A big cam is a waste with those heads.
There is nothing stopping you from fabricating your own short and larger diameter hi flow TPI runners.
Your turbo motor is all gauge boost, no horsepower.
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Old 10-07-2012, 06:56 PM
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Quote:
Originally Posted by F-BIRD'88 View Post
get rid of the heads. You are not going to make any power with them. A big cam is a waste with those heads.
There is nothing stopping you from fabricating your own short and larger diameter hi flow TPI runners.
Your turbo motor is all gauge boost, no horsepower.
i wouldnt say no power with those heads , i know somone with a dragster that runs a sbc 355 with 882's and twin turbos and made over 1000hp on an engine dyno granted this was on methanol and not gas


only thing stoping me form fabing my own runners is the fact i dont have a tig machine capable of welding aluminum right now, otherwise i would have finished the lt1 intake or fabricated new runners for the tpi.

guy over on tgo actually has a nice thread on his fabricated shorter/larger diamiter tpi runners and it didnt cost to much, and they worked great
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