24x 355 on dyno
01-12-2013, 10:42 PM
#1
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24x 355 on dyno Got my trans am on a friends dyno today to do some wot tuning. I was shooting for 400 to the wheels but I think the stock tb is holding It back. Was pulling at tad bit of vacuum upstairs. None the less though it put down 385 hp at 6700 rpm and 340 ft lbs of torque at 4700 rpm. I really wasnt after a huge number to burn the world down with when i built the engine as much as i was a broad torque curve. It didnt fail to impress me there. Im pretty happy with it overall. That was through a automatic with a 3500 vigilante converter and 4.11 gears. I will get a graph uploaded tomorrow.
01-12-2013, 11:16 PM
#3
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No I haven't been to the track since. Still in the tuning stage. Motor is a 11.3:1 355 with a small ai cam and stock lt1 heads that we cncd at p&m performance. They are a small 182 CC runner with 2.02/1.6 valves. Bottom half is all forged.
01-13-2013, 06:38 AM
#4
IMO don't base your belief of restriction by the stock TB on just vacuum numbers from the pcm.
Given the location of the MAP I believe that by the time you get into heads/cam motors you cause some Bernoulli effect. If school was long enough ago you forget that one just Wiki it.
Given the location of the MAP I believe that by the time you get into heads/cam motors you cause some Bernoulli effect. If school was long enough ago you forget that one just Wiki it.
01-13-2013, 06:44 AM
#5
Those arent terrible numbers if thats a small ai cam and ported heads through a heavy 3500 stall and what i assume is a 9" or 12 bolt sucking more power. Id be pretty happy with those results. Your still in the tunning stages so im sure with some more tweaking it will only get better.
01-13-2013, 07:29 AM
#7
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Yes sir sure enough. Fuel shut off was at 6800 and i had to be somewhere at 5 yesterday so I ran out of time to move it on up to 7300 so I could find the top of my valve train to know its limits. Torque peak was at 4700. 2k rpm spread it good stuff imo.
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01-13-2013, 07:32 AM
#8
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Those arent terrible numbers if thats a small ai cam and ported heads through a heavy 3500 stall and what i assume is a 9" or 12 bolt sucking more power. Id be pretty happy with those results. Your still in the tunning stages so im sure with some more tweaking it will only get better.
01-13-2013, 07:58 AM
#9
What are the cam specs? I'm wondering about that 6700 peak too, as well as the tq peak at 4700. If it's really "a small ai cam", then the first two things I'd suspect are:
1. the tune is really off in the mid rpm range,
2. the cam is retarded from where it should be.
Not bad numbers at all considering your setup, but I think there's more left in it.
1. the tune is really off in the mid rpm range,
2. the cam is retarded from where it should be.
Not bad numbers at all considering your setup, but I think there's more left in it.
Last edited by bowtienut; 01-13-2013 at 08:21 AM.
01-13-2013, 08:04 AM
#10
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[QUOTE=96capricemgr;17054107]IMO don't base your belief of restriction by the stock TB on just vacuum numbers from the pcm.
Given the location of the MAP I believe that by the time you get into heads/cam motors you cause some Bernoulli effect. If school was long enough ago you forget that one just Wiki it.[/QUOTE
I'm sure the Tb isn't 15 HP but when you work at a machine shop any excuse is good enough to bore the stock unit and cut some blades out and thin the shafts. I see carbed motors pull vacuum on the engine dyno but you also have a booster hanging in the air path and a plenum full of fuel with the air. With a dry manifold throwing more tb at it won't kill low end torque from lack of booster signal. So I say why not haha
Given the location of the MAP I believe that by the time you get into heads/cam motors you cause some Bernoulli effect. If school was long enough ago you forget that one just Wiki it.[/QUOTE
I'm sure the Tb isn't 15 HP but when you work at a machine shop any excuse is good enough to bore the stock unit and cut some blades out and thin the shafts. I see carbed motors pull vacuum on the engine dyno but you also have a booster hanging in the air path and a plenum full of fuel with the air. With a dry manifold throwing more tb at it won't kill low end torque from lack of booster signal. So I say why not haha
01-13-2013, 08:21 AM
#11
I'm sure the Tb isn't 15 HP but when you work at a machine shop any excuse is good enough to bore the stock unit and cut some blades out and thin the shafts. I see carbed motors pull vacuum on the engine dyno but you also have a booster hanging in the air path and a plenum full of fuel with the air. With a dry manifold throwing more tb at it won't kill low end torque from lack of booster signal. So I say why not haha
You're certainly in the airflow range where it will help, and sticking to the stock TB IAC circuit will have no downside.
01-13-2013, 08:34 AM
#12
[QUOTE=wht97ws6ta;17054177] He is trying to explain to you that LT1s most always show the MAP dropping off at high RPM due to it's location in a stock manifold.
His point is your not pulling that much (if any) vacuum at your power & RPM level. He is absolutely correct. If you don't know about Bernoulli effect, think of a carb booster: air flowing past it causes vacuum in it's passage.
The stock TB will support 600+ fwhp on a 360" engine without pulling a lot of vacuum at 8000 RPM. Ask me how I know.
I also agree that your power peaks a tad high for that power level. I have not seen many under 450 rwhp peak that high. I would probably recheck your intake lobe location. Sounds retarded to me also.
IMO don't base your belief of restriction by the stock TB on just vacuum numbers from the pcm.
Given the location of the MAP I believe that by the time you get into heads/cam motors you cause some Bernoulli effect. If school was long enough ago you forget that one just Wiki it.[/QUOTE
I'm sure the Tb isn't 15 HP but when you work at a machine shop any excuse is good enough to bore the stock unit and cut some blades out and thin the shafts. I see carbed motors pull vacuum on the engine dyno but you also have a booster hanging in the air path and a plenum full of fuel with the air. With a dry manifold throwing more tb at it won't kill low end torque from lack of booster signal. So I say why not haha
Given the location of the MAP I believe that by the time you get into heads/cam motors you cause some Bernoulli effect. If school was long enough ago you forget that one just Wiki it.[/QUOTE
I'm sure the Tb isn't 15 HP but when you work at a machine shop any excuse is good enough to bore the stock unit and cut some blades out and thin the shafts. I see carbed motors pull vacuum on the engine dyno but you also have a booster hanging in the air path and a plenum full of fuel with the air. With a dry manifold throwing more tb at it won't kill low end torque from lack of booster signal. So I say why not haha
His point is your not pulling that much (if any) vacuum at your power & RPM level. He is absolutely correct. If you don't know about Bernoulli effect, think of a carb booster: air flowing past it causes vacuum in it's passage.
The stock TB will support 600+ fwhp on a 360" engine without pulling a lot of vacuum at 8000 RPM. Ask me how I know.
I also agree that your power peaks a tad high for that power level. I have not seen many under 450 rwhp peak that high. I would probably recheck your intake lobe location. Sounds retarded to me also.
Last edited by Ed Wright; 01-13-2013 at 08:42 AM.
01-13-2013, 01:11 PM
#13
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[QUOTE=Ed Wright;17054222]
He is trying to explain to you that LT1s most always show the MAP dropping off at high RPM due to it's location in a stock manifold.
His point is your not pulling that much (if any) vacuum at your power & RPM level. He is absolutely correct. If you don't know about Bernoulli effect, think of a carb booster: air flowing past it causes vacuum in it's passage.
The stock TB will support 600+ fwhp on a 360" engine without pulling a lot of vacuum at 8000 RPM. Ask me how I know.
I also agree that your power peaks a tad high for that power level. I have not seen many under 450 rwhp peak that high. I would probably recheck your intake lobe location. Sounds retarded to me also. I Know all about the Bernoulli effect, nothing new to me. I also understand where he is coming from as well. I wasnt basing it off of map signal. I had a vacuum guage hooked up to one of the small nipples in the middle right side of the plenum. It didnt pull much vacuum at all, but im pretty sure a 355 close to 100% VE at 7000 RPM will come real close if not exceed the cfm that a stock unit will flow as well as the stock maf. Im just trying to look at the complete induction system as a whole unit. If it only picked me up 1 mph in the quarter id do it. As high as the motor is peaking and the 4.11 gears will put me in the upper revs alot through the quarter so i say go for it. Is it practical.... No probly not but i do inpractical things from time to time. Just another machining excersize to me.
Yes the camshaft is in 1 degree retarded. It was pinned 2 degrees advanced from ai at 106 ICL. I didnt care for 230 PSI of cyl pressure on pump gas so i backed it up 3 degrees. The LSA is in the midst of that statement just do the math.
He is trying to explain to you that LT1s most always show the MAP dropping off at high RPM due to it's location in a stock manifold.
His point is your not pulling that much (if any) vacuum at your power & RPM level. He is absolutely correct. If you don't know about Bernoulli effect, think of a carb booster: air flowing past it causes vacuum in it's passage.
The stock TB will support 600+ fwhp on a 360" engine without pulling a lot of vacuum at 8000 RPM. Ask me how I know.
I also agree that your power peaks a tad high for that power level. I have not seen many under 450 rwhp peak that high. I would probably recheck your intake lobe location. Sounds retarded to me also.
Yes the camshaft is in 1 degree retarded. It was pinned 2 degrees advanced from ai at 106 ICL. I didnt care for 230 PSI of cyl pressure on pump gas so i backed it up 3 degrees. The LSA is in the midst of that statement just do the math.
01-13-2013, 01:22 PM
#14
Could have left the cam up. You do have reverse cooling.
Even Speed Density was only about 1/2 MPH in the 1/4 mile on mine, back-to-back, same day. No ET difference. My 383" only picked up a couple hundredths and almost 1 MPH in SD mode.
A 52mm TB did nothing for my 355". Had a 58mm on my 383" just because I had one. Took it for part of the money a kid owed me for some parts. Probably worth a little on the 383".
Even Speed Density was only about 1/2 MPH in the 1/4 mile on mine, back-to-back, same day. No ET difference. My 383" only picked up a couple hundredths and almost 1 MPH in SD mode.
A 52mm TB did nothing for my 355". Had a 58mm on my 383" just because I had one. Took it for part of the money a kid owed me for some parts. Probably worth a little on the 383".
Last edited by Ed Wright; 01-13-2013 at 01:28 PM.
01-13-2013, 01:51 PM
#15
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Cam is 1 degree retarded. Called for a 106 centerline but i didnt care for 230 lbs of cyl pressure on pump gas so i backed it up 3 degrees to knock some psi out. Do the math and you will see the lsa in there.
01-13-2013, 01:57 PM
#16
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Cam is 1 degree retarded. Called for a 106 centerline but i didnt care for 230 lbs of cyl pressure on pump gas so i backed it up 3 degrees to knock some psi out. Do the math and you will see the lsa in there.
01-13-2013, 02:08 PM
#17
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Thread Starter
Cam is 1 degree retarded. Called for a 106 centerline but i didnt care for 230 lbs of cyl pressure on pump gas so i backed it up 3 degrees to knock some psi out. Do the math and you will see the lsa in there.
01-13-2013, 03:14 PM
#18
It is an LT1 230psi cranking compression is not a problem. Heck in my experience 245-250 is not a problem. I know on some other engines it likely would be an issue but not this one.
I think a larger TB will gain you something I just wanted to make a point of not trusting the MAP sensor.
If I were you I would be looking at bowtienut's setup and asking myself where the other 40hp/40tq came from especially since your's peaks higher.
I think a larger TB will gain you something I just wanted to make a point of not trusting the MAP sensor.
If I were you I would be looking at bowtienut's setup and asking myself where the other 40hp/40tq came from especially since your's peaks higher.
01-13-2013, 04:38 PM
#19
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My Lord my phone is jacking around with me. Sorry about the triple post. Didn't want to post that at all.
Apparently my low power and high peak Rpm is concerning some people on here. I really dont care if sich and suches motor is x amount stronger than mine with a lower rpm. I dont care if your lt1 runs just fine on 250 psi of cyl pressure. Mine will not because im not wasting my time to go back in it to find out. I was just posting my results for the hell of it. It wasnt nothing to brag about because those arent big fat numbers to boast. If you dont like how i built it then lucky for you you wont have to drive it.
Apparently my low power and high peak Rpm is concerning some people on here. I really dont care if sich and suches motor is x amount stronger than mine with a lower rpm. I dont care if your lt1 runs just fine on 250 psi of cyl pressure. Mine will not because im not wasting my time to go back in it to find out. I was just posting my results for the hell of it. It wasnt nothing to brag about because those arent big fat numbers to boast. If you dont like how i built it then lucky for you you wont have to drive it.
