Chalk one up for the ricers
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From: Cleveland, Ohio
Chalk one up for the ricers
I raced a 240 sx today on the highway, and lost. The guy only slowly pulled on me (about 1/2 a car), but I lost just the same. We pulled over to "talk" so I got to hear all about his boost leak so that's why he only had 19 PSI. Also, 'It's just a 4 banger' got thrown arround. He had a real good time with it. He also sugested we meet at the track ASAP. This was quickly fallowed by his braging over a 109 trap speed. It's enough to make me sick, because my car is built up. I have Heads (279 @ .600 I 189 @ .600 E, headders, big cam (GM 847 ish), forged internals, balanced, built T-56 w/ viper output, Moser 12 bolt, full BMR suspension + Q-A1's, and N20. I am only getting 350 RWHP (shooting for 420 RWHP at least). I know for a fact my set up should be able to flat out destroy that car N/A, but untill I find my missing HP I am forced to loose to lesser cars. I think the factory TB is hurting me, also my exhaust may be restrictive. The reason I think this is because the car never sees 100 KPA on the map sensor, it's about 80-86 KPA @ WOT 6500 RPM. So there has to be a restriction some where. I won't be able to be at the track this friday, but I will see this guy again, and when I do I am going to be ready, and I am going to have the 200 shot ready for any one of his friends.
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Joined: Apr 2003
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From: Irmo, S.C
I doubt it's your throttle body. On my last vette, it was making 470rwhp w/the stock 48mm tb. I switched to a 52 mm and saw no hp increase. The car felt a little more responsive to throttle input, but there was no hp gain. Did you degree the cam or install it straight up? What about your ecm....did you tune it at all? Have a dyno'd with a sniffer to see what your a/f is doing? I'd look at everything else before I worried about the throttle body.
Jason
Jason
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Joined: Dec 1998
Posts: 455
From: Cleveland, Ohio
The cam was installed with the dot's alligned. Degreeing a cam only varafies it's position (whitch was correct based on the ICL), you are unable to adjust the timing, cam advance is ground into the cam, more over, I recall seeing something arround here saying that advancing the cam will give false imputs to the opti. The car was dyno tuned the A/F was 12.7. I think there is a restriction due to the fact the maf only saw 312 GM/S and the Map sensor never exceeded 89 kpa, so something is not right. If anyone out there has and Idea I am open too hear it.
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Joined: Mar 1999
Posts: 477
From: Houston, TX
I'd think there is a significant restriction in front of the plenum for his MAP to read 80 kpa... how much the stock throttle body is contributing to that, I don't know. I've seen a pretty significant gain going to a 58mm TB, though. 
Originally posted by yellavette
I doubt it's your throttle body. On my last vette, it was making 470rwhp w/the stock 48mm tb. I switched to a 52 mm and saw no hp increase. The car felt a little more responsive to throttle input, but there was no hp gain. Did you degree the cam or install it straight up? What about your ecm....did you tune it at all? Have a dyno'd with a sniffer to see what your a/f is doing? I'd look at everything else before I worried about the throttle body.
Jason
I doubt it's your throttle body. On my last vette, it was making 470rwhp w/the stock 48mm tb. I switched to a 52 mm and saw no hp increase. The car felt a little more responsive to throttle input, but there was no hp gain. Did you degree the cam or install it straight up? What about your ecm....did you tune it at all? Have a dyno'd with a sniffer to see what your a/f is doing? I'd look at everything else before I worried about the throttle body.
Jason
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Joined: Apr 2003
Posts: 26
From: Irmo, S.C
It may be different for Corvettes than z28's....but in the Vette community, throttle bodies are laughed at as a hp mod.....unless we're talking 9 sec. rides. In fact, my brother made 630 rwhp with the stock 48mm....so while it may be worthwhile in the Z, I doubt that's what's costing this guy 70 hp. Maybe the tb butterflies aren't opening fully? I'd check the voltage on the TPS sensor as well.
Jason
Jason
Originally posted by EddieP
I'd think there is a significant restriction in front of the plenum for his MAP to read 80 kpa... how much the stock throttle body is contributing to that, I don't know. I've seen a pretty significant gain going to a 58mm TB, though.
I'd think there is a significant restriction in front of the plenum for his MAP to read 80 kpa... how much the stock throttle body is contributing to that, I don't know. I've seen a pretty significant gain going to a 58mm TB, though.
Last edited by yellavette; May 27, 2004 at 04:12 PM.
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Joined: Apr 2003
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From: Irmo, S.C
We picked up close to 60 rw on my bro's car by installing the cam 3 degrees advance. Of course, that's what the manufacturer stated from the get go, but the idiot who installed it the first time put it in straight up. Never had any problems with the optispark....but of course, this is in a Vette...so who knows. Just throwing out ideas based on past experiences.
When I first started on my Vette, I couldn't get past 401 rwhp. Turned out when we put a sniffer on it, I had a nice lean spot when the boost peaked. Tuned it out and picked up 70 rw.
Jason
When I first started on my Vette, I couldn't get past 401 rwhp. Turned out when we put a sniffer on it, I had a nice lean spot when the boost peaked. Tuned it out and picked up 70 rw.
Jason
Originally posted by 526 SS 96
The cam was installed with the dot's alligned. Degreeing a cam only varafies it's position (whitch was correct based on the ICL), you are unable to adjust the timing, cam advance is ground into the cam, more over, I recall seeing something arround here saying that advancing the cam will give false imputs to the opti. The car was dyno tuned the A/F was 12.7. I think there is a restriction due to the fact the maf only saw 312 GM/S and the Map sensor never exceeded 89 kpa, so something is not right. If anyone out there has and Idea I am open too hear it.
The cam was installed with the dot's alligned. Degreeing a cam only varafies it's position (whitch was correct based on the ICL), you are unable to adjust the timing, cam advance is ground into the cam, more over, I recall seeing something arround here saying that advancing the cam will give false imputs to the opti. The car was dyno tuned the A/F was 12.7. I think there is a restriction due to the fact the maf only saw 312 GM/S and the Map sensor never exceeded 89 kpa, so something is not right. If anyone out there has and Idea I am open too hear it.
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Joined: Mar 1999
Posts: 477
From: Houston, TX
Jason,
It's no different between vettes and f-bodies... Was your 470 rwhp and your brother's 630 rwhp rides NA motors? My guess is not... The fact that you can make that power with a power adder and the stock TB really doesn't say much about the effectiveness of the stock TB in his NA setup.
It's no different between vettes and f-bodies... Was your 470 rwhp and your brother's 630 rwhp rides NA motors? My guess is not... The fact that you can make that power with a power adder and the stock TB really doesn't say much about the effectiveness of the stock TB in his NA setup.
Originally posted by yellavette
It may be different for Corvettes than z28's....but in the Vette community, throttle bodies are laughed at as a hp mod.....unless we're talking 9 sec. rides. In fact, my brother made 630 rwhp with the stock 48mm....so while it may be worthwhile in the Z, I doubt that's what's costing this guy 70 hp. Maybe the tb butterflies aren't opening fully? I'd check the voltage on the TPS sensor as well.
Jason
It may be different for Corvettes than z28's....but in the Vette community, throttle bodies are laughed at as a hp mod.....unless we're talking 9 sec. rides. In fact, my brother made 630 rwhp with the stock 48mm....so while it may be worthwhile in the Z, I doubt that's what's costing this guy 70 hp. Maybe the tb butterflies aren't opening fully? I'd check the voltage on the TPS sensor as well.
Jason
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Joined: Apr 2003
Posts: 26
From: Irmo, S.C
No, both motors were blown. But what we're talking about here is the ability to flow/move air. If a 48 mm tb could create the restriction in airflow this guy has, then it'd create an even larger restriction on our cars which had to move more air than his does. I get your point about not seeing a hp improvement because the cars were blown....and that's true. Having a 14 lbs air pump can overcome a lot of imperfections.....but airflow is airflow, and if the stock 48 mm can move enough CFM to support 700 hp, then I don't see how it could be a bottle neck on this guy's 450 hp car?
Jason
Jason
Originally posted by EddieP
Jason,
It's no different between vettes and f-bodies... Was your 470 rwhp and your brother's 630 rwhp rides NA motors? My guess is not... The fact that you can make that power with a power adder and the stock TB really doesn't say much about the effectiveness of the stock TB in his NA setup.
Jason,
It's no different between vettes and f-bodies... Was your 470 rwhp and your brother's 630 rwhp rides NA motors? My guess is not... The fact that you can make that power with a power adder and the stock TB really doesn't say much about the effectiveness of the stock TB in his NA setup.
Last edited by yellavette; May 28, 2004 at 11:00 AM.
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Joined: Mar 1999
Posts: 477
From: Houston, TX
Originally posted by yellavette
but airflow is airflow, and if the stock 48 mm can move enough CFM to support 700 hp, then I don't see how it could be a bottle neck on this guy's 450 hp car?
Jason
but airflow is airflow, and if the stock 48 mm can move enough CFM to support 700 hp, then I don't see how it could be a bottle neck on this guy's 450 hp car?
Jason
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Joined: Mar 1999
Posts: 477
From: Houston, TX
Originally posted by yellavette
If the stock 48 mm TB can handle X amount of CFM from on a supercharged car, it can handle that same amount of CFM on a n/a car.
If the stock 48 mm TB can handle X amount of CFM from on a supercharged car, it can handle that same amount of CFM on a n/a car.
No offense, but what you're saying is absolute nonsense. Let me see if I can explain it a little better. On a N/A car, all you have is atmospheric pressure pushing the air into the motor - because of this, the max airflow potential of the TB is fixed (aside from changes from going to a different elevation, different air temp, ect.). If you have a FI setup, you are pushing the air into the motor with more pressure... the more pressure (i.e., boost) you can push with, the more the TB will flow. The airflow potential of the TB in an FI setup is NOT FIXED . If you had a big enough and efficient enough air compressor, you could make the TB flow whatever CFM you wanted (within reason).
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Joined: Apr 2003
Posts: 26
From: Irmo, S.C
That wasn't the point I was trying to make at all. What I'm getting at is that the 58 mm tb flows 1600 cfm if I recall correctly. The 48 mm tb flows around 1000-1200 cfm (don't know exactly). The only way you'd gain hp by switching to the larger TB is if you are pushing more CFM than what the stock TB can flow (thus creating a bottleneck). If his car is flowing 1000 cfm at WOT (for instance), and the stock TB can handle 1200 cfm, then there'd be absolutely no gain by switching to a 1600 cfm TB. And I know that the stock TB is capable of flowing enough CFM for 465 rwhp n/a as that's what my bro's car made before the SC kit....so IMO increasing the CFM of the TB by 400 isn't going to net the 70 rwhp this guy's looking for.....do you disagree? In fact, I'd bet you that no one can show me a dyno gain of more than 10 hp when switching TB's on a sub 500 hp car. No one on the vette forum could find ANY gains in peak hp.
Jason
Jason
Originally posted by EddieP
WRONG!!! airflow is NOT airflow when you are compairing a boosted motor to NA. At 14.7 psi of boost, you are effectively doubling the airflow of the TB over an identical NA setup. NA motors are limited to atmospheric pressure to pushing air through the TB - with an FI motor, you can increase the effective CFM of airflow through the TB flow by cranking up the boost.
WRONG!!! airflow is NOT airflow when you are compairing a boosted motor to NA. At 14.7 psi of boost, you are effectively doubling the airflow of the TB over an identical NA setup. NA motors are limited to atmospheric pressure to pushing air through the TB - with an FI motor, you can increase the effective CFM of airflow through the TB flow by cranking up the boost.
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Joined: Mar 1999
Posts: 477
From: Houston, TX
Jason,
I'm really having a hard time following your 'point' with all your misinformation. 1st off, I never said it would land him 70 rwhp - I don't think he's even 'missing' 70 rwhp.... my guess is that around 30rwhp is possible with some tuning and a better intact tract that gets his MAP closer to 100 KPA. 2nd, a 58mm TB doesn't flow anywhere NEAR 1600 cfm - they are rated at 1000 cfm. The stocker is only rated at [/b] ~625 cfm[/b], which is fine for a stocker or bolt-on car, but small for a good H/C setup and inadequate for a stroker.
Furthermore, you are also incorrect when you say using an TB that flows more than the engine can consume will show 'absolutely no gain'. I see people say this all the time, and like you, they are wrong . Although it might be small, there will be a VE gain from an oversized TB over a TB that flows exactly what the engine uses.
I'm really having a hard time following your 'point' with all your misinformation. 1st off, I never said it would land him 70 rwhp - I don't think he's even 'missing' 70 rwhp.... my guess is that around 30rwhp is possible with some tuning and a better intact tract that gets his MAP closer to 100 KPA. 2nd, a 58mm TB doesn't flow anywhere NEAR 1600 cfm - they are rated at 1000 cfm. The stocker is only rated at [/b] ~625 cfm[/b], which is fine for a stocker or bolt-on car, but small for a good H/C setup and inadequate for a stroker.
Furthermore, you are also incorrect when you say using an TB that flows more than the engine can consume will show 'absolutely no gain'. I see people say this all the time, and like you, they are wrong
. Although it might be small, there will be a VE gain from an oversized TB over a TB that flows exactly what the engine uses.
Originally posted by yellavette
That wasn't the point I was trying to make at all. What I'm getting at is that the 58 mm tb flows 1600 cfm if I recall correctly. The 48 mm tb flows around 1000-1200 cfm (don't know exactly). The only way you'd gain hp by switching to the larger TB is if you are pushing more CFM than what the stock TB can flow (thus creating a bottleneck). If his car is flowing 1000 cfm at WOT (for instance), and the stock TB can handle 1200 cfm, then there'd be absolutely no gain by switching to a 1600 cfm TB. And I know that the stock TB is capable of flowing enough CFM for 465 rwhp n/a as that's what my bro's car made before the SC kit....so IMO increasing the CFM of the TB by 400 isn't going to net the 70 rwhp this guy's looking for.....do you disagree? In fact, I'd bet you that no one can show me a dyno gain of more than 10 hp when switching TB's on a sub 500 hp car. No one on the vette forum could find ANY gains in peak hp.
Jason
That wasn't the point I was trying to make at all. What I'm getting at is that the 58 mm tb flows 1600 cfm if I recall correctly. The 48 mm tb flows around 1000-1200 cfm (don't know exactly). The only way you'd gain hp by switching to the larger TB is if you are pushing more CFM than what the stock TB can flow (thus creating a bottleneck). If his car is flowing 1000 cfm at WOT (for instance), and the stock TB can handle 1200 cfm, then there'd be absolutely no gain by switching to a 1600 cfm TB. And I know that the stock TB is capable of flowing enough CFM for 465 rwhp n/a as that's what my bro's car made before the SC kit....so IMO increasing the CFM of the TB by 400 isn't going to net the 70 rwhp this guy's looking for.....do you disagree? In fact, I'd bet you that no one can show me a dyno gain of more than 10 hp when switching TB's on a sub 500 hp car. No one on the vette forum could find ANY gains in peak hp.
Jason
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Joined: Mar 1999
Posts: 477
From: Houston, TX
Originally posted by yellavette
In fact, I'd bet you that no one can show me a dyno gain of more than 10 hp when switching TB's on a sub 500 hp car. No one on the vette forum could find ANY gains in peak hp.
Jason
In fact, I'd bet you that no one can show me a dyno gain of more than 10 hp when switching TB's on a sub 500 hp car. No one on the vette forum could find ANY gains in peak hp.
Jason
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Joined: Apr 2003
Posts: 26
From: Irmo, S.C
<[If the stock 48 mm TB can handle X amount of CFM from on a supercharged car, it can handle that same amount of CFM on a n/a car.>
How did you even quote this??? I typed that and deleted it 1 sec. later as that's not what I wanted to say.
Jason
QUOTE]Originally posted by EddieP
Jason,
No offense, but what you're saying is absolute nonsense. Let me see if I can explain it a little better. On a N/A car, all you have is atmospheric pressure pushing the air into the motor - because of this, the max airflow potential of the TB is fixed (aside from changes from going to a different elevation, different air temp, ect.). If you have a FI setup, you are pushing the air into the motor with more pressure... the more pressure (i.e., boost) you can push with, the more the TB will flow. The airflow potential of the TB in an FI setup is NOT FIXED . If you had a big enough and efficient enough air compressor, you could make the TB flow whatever CFM you wanted (within reason). [/QUOTE]
How did you even quote this??? I typed that and deleted it 1 sec. later as that's not what I wanted to say.
Jason
QUOTE]Originally posted by EddieP
Jason,
No offense, but what you're saying is absolute nonsense. Let me see if I can explain it a little better. On a N/A car, all you have is atmospheric pressure pushing the air into the motor - because of this, the max airflow potential of the TB is fixed (aside from changes from going to a different elevation, different air temp, ect.). If you have a FI setup, you are pushing the air into the motor with more pressure... the more pressure (i.e., boost) you can push with, the more the TB will flow. The airflow potential of the TB in an FI setup is NOT FIXED . If you had a big enough and efficient enough air compressor, you could make the TB flow whatever CFM you wanted (within reason). [/QUOTE]