hey all. just wanted to get some opinions before i buy. mine is a double, and my injectors are coming so i need to find a good one to match them (30 lb. SVO's). advice on where to get them and what kind to get?

-J-

 

what makes you think you need a bigger throttle body? With 305 heads, I really don't see that motor flowing anywhere near enough air to need anything bigger than the stock 48mm unit. Until you have 350rwhp or more, the 48 will do just fine.

I'd rethink those huge injectors too.

 

Until you run out of air, I would not go with a twin 58mm TB which flows 1000 cfm.

Your injectors are going to be the problem unless you get the EPROM recalibrated.

 

They might be a problem even if he does get it recalibrated. 30lb/hr injectors, although not totally huge, are big enough that the pulse width of the squirt is going to be wicked small. It's going to effect idle quality.

A 22lb/hr injector would probably be more than enough, but no more than an SVO 24.

 

well the one's i have on there now are 24's and i've talked yo several of mechanics who say i need much bigger injectors AND throttle body, and have all suggested a twin 58. plus i got these 30 pounders for $144 and you can't argue with that

let's say you didn't know the circumstances and all you knew was that i wanted a twin 58, where should i get it and what kind is best?
-J-

 

first of all, this lt1 is from a '72 vette -two years after they started using them, so the setup is different...the stock throttle body is actually 52 and my engine needs bigger at this point.

the large injectors will be fine, i do plan on recalibrating.

lastly, my car dynoed 360 rwhp before i got it

 

GM never used a 52mm throttle body. All of them were 48, from the 190hp 86 305 right up to the LT4.

But hey, whatever floats your boat. I know that a 305 head is restricting high rpm airflow so severely that there is no possible way your motor is ever going to come close to reaching the limits of either a 24lb injector or the stock throttle body. There's a guy on thirdgen.org running 10s in his vette with 24lb injectors. What times are you running?

 

well mine is 52mm and i have no idea why anyone would change it to a throttle body never used by chevy...oh well

haven't tryed it at the track yet...i plan on it though

and i'll take the advice on the 5 mechanics i asked on the injectors..thanks anyways though

i just asked which freaking throttle body is best and where to get it...god dam

 

holley
tpis
edelbrock
lignefelter (accel)

ect

all sell throttle bodies. most of the companies make both 52mm and 58mm TBs

but like everyone else is saying, you have got to be making some big time power, to need one, and with the engine in your sig, with the heads you have, you aren't going to be out flowing the throttle blody.

here are some links

http://holley.com/HiOctn/ProdLine/Pr...B/112-512.html

http://www.tpis.com/

http://www.edelbrock.com/automotive/...le_bodies.html

http://www.lingenfelter.com/lingenfe...=16&pf%5Fid=50

 

Go ahead and trust your 5 mechanics. I learned a long time ago that a jack of all trades (i.e. mechanic) doesn't know **** about how to mod my specific car. Even the GM mechanics don't have any clue about tpi except how to follow the flow charts in the service manuals in order to fix your problem.

When it comes to specific platforms like TPI, the experts are the guys on these boards that have spent hundreds of hours and thousands of dollars on mods, and seen the results first hand. After you and 20 other people all waste your money on the same useless mod, the learning process starts to take form.

Try the TPI forum on thirdgen.org. That forum is packed with people that actually mod their TPI cars and know what's happening. Rather than trust their mechanic that makes more money every time they decide to give him another pile of parts to install, or say what they want to hear to get them out of their garage bay so they can get back to work, they know from experience. Just like me. Just like everybody else here that's trying to help you save money and get that car to run right. For what those unnecessary injectors and unnecessary throttle body cost, you could buy a real set of heads (vortecs or d-port vette heads) and actually start to get some real performance out of your car. Instead, you want to **** more money into replacing stuff that's working ok.

But hey... it's not my money. For what it's worth, the TPIS throttle body or the AS&M unit (which I think is a TPIS) are the best. Of course, they cost more than a new set of Vortec heads. I've got a holley 52 on my IROC (which didn't do sh*t by the way) and I'm happy with the quality, but others have complained about the TPS sensor not fitting (you need to file it) and with the throttle blades not opening/closing properly, but I haven't had those problems. I've got a TPIS on my Vette, but I don't know what size because I haven't checked since I bought the car. If it's a 58, I'm replacing it with a 48. If it's a 52 I'll keep it.

Most people with the BBK complain that it's a cheap POS. The Edelbrock is a BBK.

 

I had a friend with a stock L98 Vette and he went one half of a tenth slower after he installed the 58mm TB. Probably messed up the airflow and caused some turbulance in the manifold. You still need to have the rest of the intakes fixed to take advantage of the larger TB.

 

k first of all you don't know the main guy i talk to, and he knows more than you can imagine about this subject, has built many camaros and now just finished an iroc that he pushes to 8.2 quarter without nos... i tend to listen to what he says, and you would too if you knew him. he is not a dealership mechanic and is not overly paid, you have intercepted a bad stereotype.

plus, it seems obvious to me that the point of any engine performance enhancement part is to increase either the air flow, the spark, or the fuel. this means that the bigger the flow, the more power, if you have everything in proportion (i.e. injectors)

my error which probably caused some of this is that i believed the previous owner on what size heads i have. they are actually 202's
-J-

 

yes, air + gas = power well usualy

but the problem with TPI isn't that the throttle body is a restriction, the problem is everything else is. unless you fix all the other restrictions in the TPI system, the only way a throttle body is going to make you any faster is the wieght savings from you pocket book.

now if you had a stealth ram, big **** 220cc heads, and you could actualy get that much air into an engine, then yes a bigger TB might be needed. but if you are still using a factory TPI system, i can 100% promise you that the TB will do nothing for you, no matter how much air can pass through that TB, you still have runners that don't flow much, and an intake base that flows next to nothing.

 

Well, if you want as much air flow, look into the Arizona Speed & Marine Mono-Blade 58mm TB. It's about $650 and flows over 1000 I believe.
FWIW, the Ramjet 502 big block uses a 48mm TB.

 

Yes, increasing airflow and fuel flow generally helps. But, in the case of air intake, there's a tug of war between velocity and volume. Velocity keeps your low end torque high, and volume is necessary for high rpm power, i.e. horsepower. The problem is, high flow volume reduces velocity.

Now, this seems simple, but honestly the whole throttle body issue confuses me a little bit, because it would seem that any amount of airflow upstream of the plenum wouldn't have an effect on velocity, but that doesn't seem to be the case. Somebody above just mentioned that his friend's car slowed down with a 58mm throttle body. That's not a unique problem. A while back CHP did a test with Tom Keliher's car. He's a thirdgen.org friend. His car is a 13 second car that's had its share of mods. Even on his modified car, putting a 58mm throttle body on caused him to slow down. Too big of a throttle body causes a loss of low rpm power, which correlates to a loss in air velocity.

When it comes to fuel, more isn't necessarily better. You make the most power when you maintain a specific air/fuel ratio. More fuel just makes you run rich, which robs power and ruins catalytic converters. You only need to supply enough fuel to maintain a proper a/f ratio and no more.

I realize that you're in a tough position. You don't know much about this, and you don't know who to trust when you get conflicting opinions. It's easy to trust the guy with the 8 second car because he must be a genius, but that still isn't the case. His 8 second car has so very little to do with your car or mine, that most of the knowledge doesn't apply. I can guarantee that he's not running 8 second 1/4s with TPI or anything that resembles it. He's either got a custom fabricated EFI manifold with stand alone control, or he's running a carb. Neither of which has much to do with your car.

The fact is, 24lb injectors will support power far beyond what your car is making, and so will the stock throttle body. There really isn't much else I can say that'll change your mind. I guess you're going to have to buy that crap and learn for yourself. That's how I learned too.