Why is a 58mm TB too big?
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From: You guess it
Why is a 58mm TB too big?
NOS makes a really cool 58mm TB with the nitrous jets already built-in but it only comes in a 58mm TB. Why is a 58mm TB too big for an LT4? I think I wold have to open up the intake manifold and that's no problem but I'm wanting to how the engine will perform with the bigger TB. Please educate.
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From: Fredericksburg Virginia
Re: Why is a 58mm TB too big? (Bill Burkert)
Copied from a site:
Unless you are going to replace the TPI runners with larger diameter versions, there is no point in buying a 52 MM or 58 MM throttle body.
The problem is the runner restrictions. By doing other air mods that improve your intake air flow, you have maximized the flow as much as you can realistically expect to increase it without major adn expensive changes.
Also, increasing the runner diameter or installing shorter runners will cost you low end torque but only slightly increase your high end horse power. As mentioned above, unless you can run your car at very high speed, you should stick with the stock runners and enjoy the torque boost they provide.
Hope this helps!
Unless you are going to replace the TPI runners with larger diameter versions, there is no point in buying a 52 MM or 58 MM throttle body.
The problem is the runner restrictions. By doing other air mods that improve your intake air flow, you have maximized the flow as much as you can realistically expect to increase it without major adn expensive changes.
Also, increasing the runner diameter or installing shorter runners will cost you low end torque but only slightly increase your high end horse power. As mentioned above, unless you can run your car at very high speed, you should stick with the stock runners and enjoy the torque boost they provide.
Hope this helps!
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Re: Why is a 58mm TB too big? (Bill-35thAnvrsy-88)
Bill, he doesnt have a TPI intake.
A 58mm would be too big because your engine simply cant suck that much air in, a 350 doesnt need the 1000cfm that the 58 brings. It doesnt even need the 52mm.
58mm will mess up your idle, a 52mm will usually not but wont bring any performance gains either.
A 58mm would be too big because your engine simply cant suck that much air in, a 350 doesnt need the 1000cfm that the 58 brings. It doesnt even need the 52mm.
58mm will mess up your idle, a 52mm will usually not but wont bring any performance gains either.
Drifting
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From: Las Vegas Nevada
Re: Why is a 58mm TB too big? (Bill Burkert)
Send the intake to get ported, along with your heads, then the 58 will be fit well and you'll be that much faster on and off the bottle :)
I know, not a small expense.. but should be worth its weight.
On the other side of that..... Some beleive that you cant really over do a TB because it doesnt regulate the fuel like a carb. It shouldnt mess with idle at all because the only gains are when the throttle is being cracked open...
Its been debated over and over again with no winners :p:
Now that I think about it, the LT4 heads are supposed to flow rather well, so do the manifold ($300 exchange from Lingenfelter for modding LT4 manifold).
Enjoy whatever you decide :)
Matt
I know, not a small expense.. but should be worth its weight.
On the other side of that..... Some beleive that you cant really over do a TB because it doesnt regulate the fuel like a carb. It shouldnt mess with idle at all because the only gains are when the throttle is being cracked open...
Its been debated over and over again with no winners :p:
Now that I think about it, the LT4 heads are supposed to flow rather well, so do the manifold ($300 exchange from Lingenfelter for modding LT4 manifold).
Enjoy whatever you decide :)
Matt
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From: Oak Harbor WA
Re: Why is a 58mm TB too big? (VetteRacer282)
The TB does regulate air intake, so by going to a bigger intake of air you will loose intake velocity which lowers low end torque. The one thing we all would want on the street. Also, more air in a Nitrous application isn't a good thing because it brings about lean conditions. So you have to increase the proper amount of fuel as well. Now, without the use of a turbo or supercharger, you aren't going to get more air into the engine without other mods to increase airflow.
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From: Windermere FL
Re: Why is a 58mm TB too big? (Goody)
You will loose velocity with that large a TB. It will work if the rest of the motor is set up for it but I wouldn't use one for most 350 and even mild stroker combos. The stock or 52mm will work fine. For a blown or radical stroker, the 58mm is the ticket.
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From: You guess it
Re: Why is a 58mm TB too big? (Bill Burkert)
I'd like to thank everyone for bringing me up to speed :D on the TB info. I was thinking about using the Holley 58mm with nitrous jets built in but it looks like that isn't the solution. I also think I'm going to take the 52mm one off too and put the stock one back on.
Thanks for edumication! :seeya
Thanks for edumication! :seeya
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From: Sachse Texas
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Re: Why is a 58mm TB too big? (92TripleBlack)
I have run all of them on my 396 motor...stock 48 (just to get to the shop), BBK 52, and now run a Holley 58mm. The main difference that I can personally vouch for is the throttle response. The smaller the throttle body, the more gradual the pedal will allow the power to come on. The larger the throttle body, the more sensitive your pedal will be since a very small amount of throttle will ingest a lot more air into the plenum compared to the smaller throttle bodies.
I have also been able to feel a fair difference in low end torque between the 48 and 58mm versions. It is not a major difference, but it feels like there is a slight difference. Take into consideration this is on a big stroke motor and not an LT4. The observations that I have made may or may not be as noticable on a LT4 motor.
I have also been able to feel a fair difference in low end torque between the 48 and 58mm versions. It is not a major difference, but it feels like there is a slight difference. Take into consideration this is on a big stroke motor and not an LT4. The observations that I have made may or may not be as noticable on a LT4 motor.
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Re: Why is a 58mm TB too big? (Denny McLain)
Well let me mix my subjective answer with some facts. The car is calibrated for x amount of airflow at x throttle position. Changing the TB messes that all up plain and simple. The result will be a more sensitive throttle pedal and a generally messed up throttle until you get to the top. At WOT you'll still flow the same amount of air and give it the same amount of fuel, so you won't see anything.
Oh, BTW, I dyno'd my car with my 48 vs my 52. I lost 4 hp with the 52. Now this was on a different dyno on a different day, so I can't say that it's anything substantial. I can however say that it didn't gain anything. So why do I still use the 52? Well I paid for it, I originally got it at a very good price, and it looks a lot better than the stocker. Performance wise, 0.
Oh, BTW, I dyno'd my car with my 48 vs my 52. I lost 4 hp with the 52. Now this was on a different dyno on a different day, so I can't say that it's anything substantial. I can however say that it didn't gain anything. So why do I still use the 52? Well I paid for it, I originally got it at a very good price, and it looks a lot better than the stocker. Performance wise, 0.
Drifting
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Re: Why is a 58mm TB too big? (Denny McLain)
Kinda sounds like nobody has actually tried it except a few. Yes they make a difference. You would not want the 58 on a stock engine. Your intake will flow the air and you have good heads they way they are. You will notice a difference by going to a 52mm. We just installed a 58 on a race car with an LT4, they have to run stock heads, intake etc. It had a BBK 52mm on it and with that being the only change the car went from qualifing 18th to 2nd by only 3 thousandths of a second. So yes it makes a difference. I had a 58MM, yes a 58 on my 86 with a stock engine and the car was awesome. At the drag strip we were shifting at 6300 RPM in a L-98
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Re: Why is a 58mm TB too big? (snaketr)
Just curious, how does your qualifying position mean anything? I have a 12 second car, I've got the timeslips to prove it and some days I can't get out of the 13's. People have good and bad days. Saying you went from qualifying x to y doesn't mean anything, way too many variables.
Also, an L98 will easily spin to 6300, it just doesn't make any power. If a 58 mm TB is all you need to make an L98 breath well than I guess the Super Ram wouldn't exist.
I'm not calling you a liar, I'm just saying that your results have too many variables to be considered fact. A dyno is not the best way to judge a car's performance, but it is indeed the ultimate :bs dectector when it comes to power increasing modifications.
Also, an L98 will easily spin to 6300, it just doesn't make any power. If a 58 mm TB is all you need to make an L98 breath well than I guess the Super Ram wouldn't exist.
I'm not calling you a liar, I'm just saying that your results have too many variables to be considered fact. A dyno is not the best way to judge a car's performance, but it is indeed the ultimate :bs dectector when it comes to power increasing modifications.
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From: Sachse Texas
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Re: Why is a 58mm TB too big? (Denny McLain)
I have never gone through the trouble of doing back to back runs for any upgrade including the throttle body. Now if I had a buddy with a Dyno you bet I would, but at $40-80 per session I do not have the funds to make sense in doing so.
I do know I was running the BBK 52 for the longest time on the 396 and getting similar dyno results as the guy I bought my motor from and he was running a 58mm tb and long tube headers to my 52mm and shorties. However, Jason at MTI thought I was leaving up to 10 hp on the table by staying with the 52mm. I honestly can not say that there is any difference in the two on my setup, but I do not have any definitive data to support my assumptions. I can tell you the Holley 58mm is much better looking under the hood than the BBK ;).
Chris
I do know I was running the BBK 52 for the longest time on the 396 and getting similar dyno results as the guy I bought my motor from and he was running a 58mm tb and long tube headers to my 52mm and shorties. However, Jason at MTI thought I was leaving up to 10 hp on the table by staying with the 52mm. I honestly can not say that there is any difference in the two on my setup, but I do not have any definitive data to support my assumptions. I can tell you the Holley 58mm is much better looking under the hood than the BBK ;).
Chris
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Re: Why is a 58mm TB too big? (Vette92)
Nathan, the qualifing position had everything to do with it. The car was much faster with the 58. Nothing else was changed in the car and the weather was the same. I am not talking about drag racing here, this was road racing. Also I am not new to the performance arena sir. The throttle body that went on that car was a throttle body we had made and is billet throttle body that we were testing. Needless to say everyone was very happy. Changing vehicles to my 86, it made power all the way to valve float. You guys do not give these motors any credit. Granted the TPI is not what it should, and my car now has a SR on it also along with a Vortech unit. Anyways the car pulled hard to 6300 so if you don't think it is making any power so be it. The car ran a 8.55 in the 1/8 on the stock engine with that 58mm body on it.
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Re: Why is a 58mm TB too big? (snaketr)
So on a road race you have even more variables. What if you went into that one turn just a little bit different. There are plenty of ways to change lap times, no driver is ever perfect. I don't care how good you may feel about a run can you really feel a difference.
Honestly when I'm drag racing a 13.2 run feels a whole lot like a 12.8 run until I get around and get my ticket. Meanwhile it's the same car. Maybe you just got lucky. In a road race event such that you describe the driver has a lot more to do with it than the car. Congrats, you learned how to drive it a little better.
As for your TPI making power all tlhe way to 6300, I'll only believe that when I see it. Cough up a dyno graph.
Honestly when I'm drag racing a 13.2 run feels a whole lot like a 12.8 run until I get around and get my ticket. Meanwhile it's the same car. Maybe you just got lucky. In a road race event such that you describe the driver has a lot more to do with it than the car. Congrats, you learned how to drive it a little better.
As for your TPI making power all tlhe way to 6300, I'll only believe that when I see it. Cough up a dyno graph.
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From: Saint joseph MI
Re: Why is a 58mm TB too big? (snaketr)
OK, I've got to know. how do you get a L98 to rev to 6,300? I've got a stock 90 that pretty much is done around 4,800-5,000 rpm. What do i need to do to get it to pull to 6,300?
Drifting
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Re: Why is a 58mm TB too big? (snaketr)
Yes there are allot of variables, but we are not talking about inexperienced drivers either. So I guess all the other Corvettes on the track just slowed down. Actually the driver could feel a difference in the car pulling through the easses and in the straights. Nathan, I do not have a dyno pull on the original engine to prove my point about my L-98. I is too late now because I have a completely different engine even though it is still technically a L-98. The TCC Corvettes which lots of them are L-98's are pulling past 6000 RPM's and they have to run stock intakes, heads, and upper plenum parts. Maybe you ought to come out to a race and see for yourself.