Larger throttle body discussion...pros and cons

[GNSCOTT]

I honestly dont think anything bigger than a bored stock throttle body is going to net any gains unless you have a car that is DEEP into the 9's.

What if you have a 10 sec GN, t-66 3 inch outlet, fm with 3inch piping and a stock tb. wouldn't that cause an obstruction?? Wouldn't the rest of the combo make a difference??I'd also pay $200 extra to have my intercooler moved out of the engine bay even if it wasn't for performance reasons, a water pump and timing chain change will justify that.

 

[Two Lane]

Originally posted by GNSCOTT


I'd also pay $200 extra to have my intercooler moved out of the engine bay

With an upgraded rad, it'll likely be $1200+.

 

[GNSCOTT]

With an upgraded rad, it'll likely be $1200+.

My car is way beyond that now, but I think a Cottons intercooler would work with minimal cooling issues. I had a V2 and ran 190 * with the ac on in 90* heat. I had a recored radiator and stock everything else. I think the problem is the tanks blocking the rad, and cottons ic is so big, the tanks don't even show, but thats another thread.

 

[REDS HOT AIR]

what the he** is this thread about ?????????????

I thought we were going to talk about throttle bodies

now can someone else give real would info on t/b swaps

I asked about on a car going in the 9's

not about how much do you think you remember about what they tried to teach you in school

no matter what they told ya hot air travels faster than cool air

 

[YGETV8]

Well, I'll admit it... I have never even attended a physics class! That said, I've always stated that some of the most important parts of the mods I do to "my" 62/65mm TBs are: bellmouthing the inlet (big step from the factory); removal of the front half of the throttle shaft (obstacle for air to have to "go around"); and enlarging/blending/radiusing (is that a word?) the inlet of the upper plenum ('nother large mismatch and step there from the factory). All these will enhance the "quality" of the airflow, not just the "quantity." I consider the enlarging the TB to 62mm at the blade and tapering it out to 65mm in back just a "plus" to having me do all the previously mentioned mods!

Most common feedback I get from my customers is better throttle response and slightly quicker spool. I would guess this to be the result of potentially greater airflow at a given blade angle. To my knowledge, I know of none of my customers who have done back to back apples to apples testing at the track as I have never received any hard data other than a flowbench test and a gentleman who quoted me his increase in MAF readings on his "hot air" car (of course, I don't remember what that was!).

MANY have run very fast on stock TBs... but if you ask, I bet they have done at least some of the "enhancements" I mentioned. Does that mean it was necessary? No, but I always believed that every little bit helps! Sweat the little things, and sooner or later, they'll add up!

 

[Ormand]

"Restriction"

Good answer, Jay. We're talking air flow here, ( a compressible fluid) and not anywhere near sonic velocities. "Choked flow", in which the smallest area actually limits the flow is NOT an issue. All you got is just a little bit of a pressure drop across the throttle body, and it should be VERY little, less than 1/2 psi. If you measure pressure at WOT, it will be highest at the turbo outlet, then there's a drop across the intercooler, a tiny drop through the up-pipe (a little higher for front mount) and another small drop across the throttle body. Changing from a 62 to a 65 to a 70 will probably change the drop from 0.5 psi to 0.47 to 0.44, or something like that- maybe even less. In other words, you will get a tiny change in pressure in the doghouse, for a relatively large expense. Jay's modified TB will give you the most gain for the least money, with fewer bad side-effects. Under cruise conditions, or other part throttle, there is no boost, or very little boost. The flow is low, too, and the throttle will be just "cracked". A bigger throttle will flow the required amount of air with a smaller crack, so you will get the impression that your car is making more power, because it will cruise at the same speed even though you don't push the pedal as far down. You get the "feeling" of improved throttle response, because a small push on the pedal will give a bigger change in throttle area than with the stock TB. But once you get to WOT, there won't be a significant difference.

 

[bruce]

While you can talk density, and volume, you need to include velocity, IMO.

using larger piping all the way thru the system lowers the air speed, and air at higher speeds has alot of inertia. So by using the lower speeds when possible, the air is more likely to have an more even distribution, when it comes time to change direction in the plenum to fill which ever intake is opening.

Thou, the 70 is to the stage of slowing some cars down from what I've heard.

While you want to avoid choke points, you also do have optimum velocities through out the system.

It's all about compromises.

FWIW, on my 87 when I took the Intercooler off, I tried a 2.25, 2.5 and 3" Uppipe. And the 3 was the hands down winner. The 2.25 was smooth as silk but seriously limited at anything over a few PSI. And the 2.5 MUCH better, and then just a slight difference for the better with the 3.

 

[JDEstill]

I will say that I had Jay modify my throttle body, and the car definitely runs better. But I attribute this to the fact that my throttle shaft seals were leaking pretty bad (I always wondered why the side of my TPS that faces the TB would get oily/dirty so fast), and Jay got that all fixed up for me. No leaks there now! I think that is the root cause of the improvement I feel.

John

 

[turbowrenchhead]

Is stock 57mm? I have a stock 87 t/b with the turbomotion intake. I am thinking of having it bored to 62mm. Would it benift me at all. Is it worth it? I have 3" manderal piping from turbo to i/c to t/b where it is shurnk down a bit to fit the t/b.

 

[The Radius Kid]

Originally posted by bruce
While you can talk density, and volume, you need to include velocity, IMO.

using larger piping all the way thru the system lowers the air speed, and air at higher speeds has alot of inertia. So by using the lower speeds when possible, the air is more likely to have an more even distribution, when it comes time to change direction in the plenum to fill which ever intake is opening.

Thou, the 70 is to the stage of slowing some cars down from what I've heard.

While you want to avoid choke points, you also do have optimum velocities through out the system.

It's all about compromises.

FWIW, on my 87 when I took the Intercooler off, I tried a 2.25, 2.5 and 3" Uppipe. And the 3 was the hands down winner. The 2.25 was smooth as silk but seriously limited at anything over a few PSI. And the 2.5 MUCH better, and then just a slight difference for the better with the 3.

 

[YGETV8]

Turbowrenchhead: yes, the stock TB is only 57mm at the blade.

 

[DonnieShort]

Wow!! I'm away for a day and this thread got going!! I wonder why, though, I was told by 2 respectable people ( vendors ) that I would see a nice gain if I installed a 70mm and upper if it wasn't needed? Other than to make a few dollars, and I really don't belive that is the case because the 2 people I talked to are better and above that ( making a quick buck ).

 

[Ormand]

$$$???

Donnie, take a look at who is running fast, and how many have the 70mm TB. Guys get well in the 11s with the STOCK TB, or a modified stock TB. There is a potential small gain to be made, but it ain't cheap, and for the same bucks, there are other things that will help more. A power plate, for example, will even out distribution better than the expensive Hemco big volume plenum and big TB. Note that velocity doesn't change as the boost goes up. Unless you choose to handicap yourself by removing the intercooler, as boost increases, the DENSITY increases, not the volume, so velocity will stay the same. Higher boost, you get more pounds/hr of mixture at the same velocity. If you go with a bigger cam, big valve heads, maybe more cubic inches, then there will be a little more to be gained by changing to a bigger throttle body.

 

[azgn]

a lot of guys get way into the 10's on a stock or near stock TB....spend your money elsewhere.....

 

[twin 93 svt]

doubts

70mm tb, power plate, and precision upper along with many other mods questioned by many members. results 119 mph at 15 lbs of boost. I'm happy! because of street racing I am surprised I left any times, but you guys are killing me. I'm sure it all goes with your combo, nobody sells that one magic go fast part that makes every one happy.

 

[DonnieShort]

Originally posted by azgn
a lot of guys get way into the 10's on a stock or near stock TB....spend your money elsewhere.....

Woody I agree, but the problem is the money is already spent which is why I started this tread. My wife got me an Accufab 70 and Precision upper and power plate combo for Father's Day and I needed some real info on this before I put it in. And if it is a bad combo move, I'd like to be able to sell it and at least get close to the money she spent back if it is still new and never used.

 

[YGETV8]

If it were me, I'd carefully bolt it on and try it. If I were to sell it without ever trying it out, I'd always wonder "what if?!"

I had one customer bolt on one of my TB/uppers and a THDP and return to the track. Swore it was the same conditions and car "settings" both times. Said he gained like over .6 and 5 mph in the 1/8th (I don't remember exactly, but it was a LOT)!

Anyway, we all know there must have been something more than "meets the eye" going on (altered state of tune, whatever). BUT... did he care?! Heck no! His car responded and he never looked back. Why, we may not know, but if it went that much faster, who are we to argue! Yes, maybe he could have gained some or all of that through tuning eventually, but it worked for him!

Anyway, my point is: try it! Your car and combo may like it! Sell it, and you'll never know.

Jay

 

[azgn]

hey Donnie, that changes everything!

put that sucker on there and if it doesn't go faster, build some stuff behind it and in front that WILL make it go faster!

put it on and enjoy......

 

[Two Lane]

Originally posted by DonnieShort


My wife got me an Accufab 70 and Precision upper and power plate combo for Father's Day

Exactly what Jason Cramer (RaceJace) of RJC Racing likes best, from extensive testing...

Run it, and never stop bragging on your wife's thoughtfulness!

 

[gndriver]

What in the Hell did you give your wife for mother's day to get all that?