52 mm throttle body dyno results
03-16-2002, 03:55 PM
#1
Race Director
Thread Starter
52 mm throttle body dyno results
As promised, I dyno'd my car with the only modification being the holley 52mm throttle body.
My previous best was 336.6 hp and 345.9 torque.
After the TB I ran 332.5 hp and 345.0 torque
I will say that this is a different dyno, although still a dynojet. It's also not as cold today as it was when I dyno'd last. I can also easily see that much variation from it just being a different dyno.
So, my professional opinion? The 52mm throttle body is a very pretty, highly polished paper weight. I'm leaving it on the car because I don't really think it hurt me any, and it might help later after I have my heads done.
My previous best was 336.6 hp and 345.9 torque.
After the TB I ran 332.5 hp and 345.0 torque
I will say that this is a different dyno, although still a dynojet. It's also not as cold today as it was when I dyno'd last. I can also easily see that much variation from it just being a different dyno.
So, my professional opinion? The 52mm throttle body is a very pretty, highly polished paper weight. I'm leaving it on the car because I don't really think it hurt me any, and it might help later after I have my heads done.
03-16-2002, 04:57 PM
#5
Team Owner
Re: 52 mm throttle body dyno results (Eduardo L98 1991)
Bluevette85- What do you refer about, gm got it right ?
03-16-2002, 04:59 PM
#6
Elite Torch Red Member
Re: 52 mm throttle body dyno results (scorp508)
Bluevette85- What do you refer about, gm got it right ?
I think he means that GM was correct in using the Throttle Body that they did. Going bigger only hurts you until you have modified the car more heavily.
I think he means that GM was correct in using the Throttle Body that they did. Going bigger only hurts you until you have modified the car more heavily.
Stock programming isn't too shabby either, I think my car is proof of that.
03-16-2002, 05:24 PM
#7
Re: 52 mm throttle body dyno results (Mr Mojo)
Stock programming isn't too shabby either, I think my car is proof of that.
03-16-2002, 06:06 PM
#9
Drifting
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Re: 52 mm throttle body dyno results (Vic'89)
Hopefully an LT4 could take advantage of this. One guy on the forum stated this a while back...
Andy,
Something interesting to keep in mind about the LT4 is the 'conspiracy' theory. Basically it goes that when GM engineers finished the LT4, it made too much power for the marketing folks. They did not want the 'new' generation LS1 to be embarassed by the 'old' LT4. I have heard from a reliable source inside GM that they changed three things:
1) The original 52mm TB was removed and a 48mm TB installed.
2) The original 'Hot' cam was replaced with a milder grind.
3) Incorrect intake manifold gaskets were installed to partially block the
intake ports.
The intake openings on a LT4 manifold are exactly 52mm in diameter.
The original intake gaskets do significantly obstruct the intake ports.
I installed a Holley billet 52mm TB, Hot cam, and the GMPP 12367777 intake gaskets along with port matching the manifold/heads and got a 50hp increase at the rear wheels.
I consider this to be the 'original' LT4 spec
Something interesting to keep in mind about the LT4 is the 'conspiracy' theory. Basically it goes that when GM engineers finished the LT4, it made too much power for the marketing folks. They did not want the 'new' generation LS1 to be embarassed by the 'old' LT4. I have heard from a reliable source inside GM that they changed three things:
1) The original 52mm TB was removed and a 48mm TB installed.
2) The original 'Hot' cam was replaced with a milder grind.
3) Incorrect intake manifold gaskets were installed to partially block the
intake ports.
The intake openings on a LT4 manifold are exactly 52mm in diameter.
The original intake gaskets do significantly obstruct the intake ports.
I installed a Holley billet 52mm TB, Hot cam, and the GMPP 12367777 intake gaskets along with port matching the manifold/heads and got a 50hp increase at the rear wheels.
I consider this to be the 'original' LT4 spec
03-16-2002, 10:24 PM
#13
Drifting
Re: 52 mm throttle body dyno results (Eduardo L98 1991)
Yes guys, I meant that GM was right using a 48mm Throttle Body for the L98. It seems to be enough for that engine. I'll stick my neck out and say that there won't be a noticible gain from cutting the screen off the MAF either. :rolleyes:
03-16-2002, 10:52 PM
#14
Team Owner
Re: 52 mm throttle body dyno results (Nathan Plemons)
Once again MODS must be done in packages to get the best performance gains. I'm using only a 52mm but I've got the cam, heads and exhaust to support it.
03-16-2002, 11:03 PM
#15
Burning Brakes
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Re: 52 mm throttle body dyno results (Nathan Plemons)
I fully believe the results, but always wondered why LPE plops 58mm's on all their 350 LT1/4 motors :confused: . If I remember correctly, the 48's flow 650 cfm, the 52's 730, and the 58's 1000. Doing the math, a 350 cid motor at 6400 rpm ingests 650cfm if it has a volumetric efficiency of 100%, which of course it doesn't, so the actual flow is less than 650, therefore I don't see how going bigger than the stock 48 would make much of a difference if any.
03-16-2002, 11:56 PM
#16
Race Director
Thread Starter
Re: 52 mm throttle body dyno results (mackeyred96)
Let me just clarify in case there is any confusion. I didn't buy the throttle body looking for a major performance gain with my current setup. I bought it because I got it at a killer price and I figured it MIGHT help after I get my cylinder heads. However since I DID buy it I thought I would dyno with that my only mod to see if there was a difference. I really attribute the loss of 4 hp to dyno / weather differences. I feel confident in saying that there was no improvement or loss by going with the 52mm throttle body on my stock displacement motor at this point.
This proves to me that the cylinder heads are the restriction at this point, too bad I already knew that. Now with a very good set of heads it MIGHT make a difference but even that is questionable. It's a matter of the maximum volume of air that the motor can flow vs what the throttle body allows. I don't think the 350 will ever actually warrant a larger TB unless it is running some kind of forced induction.
So what do I have? A very pretty polished TB that does nothing for the performance of the car at this point. So why do I have it? I'm not sure what my future plans for this motor involve, one day I might rebuild it and make a stroker out of it, in which case I will actually need the TB; thus I won't have to buy it then. Until that day it looks better than the stock piece.
This proves to me that the cylinder heads are the restriction at this point, too bad I already knew that. Now with a very good set of heads it MIGHT make a difference but even that is questionable. It's a matter of the maximum volume of air that the motor can flow vs what the throttle body allows. I don't think the 350 will ever actually warrant a larger TB unless it is running some kind of forced induction.
So what do I have? A very pretty polished TB that does nothing for the performance of the car at this point. So why do I have it? I'm not sure what my future plans for this motor involve, one day I might rebuild it and make a stroker out of it, in which case I will actually need the TB; thus I won't have to buy it then. Until that day it looks better than the stock piece.
03-17-2002, 01:07 AM
#18
Team Owner
Re: 52 mm throttle body dyno results (Nathan Plemons)
So, since you lost hp with it.. and I need a 52 with my 383 .. you're going to swap me until you get a 383 right? :jester
03-17-2002, 01:15 AM
#19
Race Director
Thread Starter
Re: 52 mm throttle body dyno results (Glock'94)
No, remember you were going to send me the 383 and I was going to send you the 350 and the T-56 tranny along with nothing required to make it work. How soon your forget.
03-17-2002, 08:27 AM
#20
Instructor
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Re: 52 mm throttle body dyno results (Nathan Plemons)
There is an excellent chance that the biggest difference that Nathan saw was from the change in dyno, rather than the change in TB. The Dynojets do adjust for atmospheric pressure and temperature, but not for humidity. Also, one dyno can vary from another considerably. Last year, for example, I went to a Dynojet south of Boston and pulled 364 RWHP peak. Without any changes, I went to a dyno day at another location in Worcester, and pulled 350 RWHP peak. Why the change??? The Worcester machine was quite new, and accurate. The newer machines have larger and heavier rollers which report the HP curve more accurately. The first machine was about 12 years old, and an earlier rev, and I understand that the earlier models had lighter rollers which were sometimes more optimistic than the newer ones. So, if you want to compare numbers, you must use the same dyno, and the same conditions, like hood up, front fan, etc. Dyno racing is not too accurate.
I don't think that a 52 TB will give you more than 1 or 2 HP, but it shouldn't take any away.
I don't think that a 52 TB will give you more than 1 or 2 HP, but it shouldn't take any away.