LQ4 Tank

Does anyone have experience with the Holley 105mm throttle body with a 105mm Hi-Ram? I've been searching all afternoon and can't find crap! It'll be force fed of course with twin 69/68's through a fully forged 370ci. I plan on purchasing the Hi-Ram soon and really wanna know about this throttle body!

stevieturbo

It would be good for an easy 2000+HP

Dustin11

A 90mm is all that's needed for a turbo car, unless you just want the larger TB. I'm making 2600 with a single 90mm.

LQ4 Tank

Are there any disadvantages to running a larger than necessary throttle body? The 105's 430 bucks brand new, so it's not like it's crazy expensive, and matches my purrty intake

stevieturbo

You can basically end up with shitty throttle resolution.

ie in the case of 105mm....it might be flowing all the air the engine can consume at only 50% opening...so the latter 50% does **** all.

Even a standard 75mm has made well over 4 figures

Dustin11

There's no real downsides. With a huge TB the car accelerates very quickly off idle with very slight throttle. The engine is getting a huge gulp of air with very little throttle. It's just what you get used to. You just have to learn to drive it so your not dry hopping the car from a stop light.

LQ4 Tank

This is what I was wanting to hear. I feel like no matter what size throttle body it is, being under boost will supply the air, the motor has no choice to but accept it to a certain extent. I just want the greatest most efficient flow I can get for my motor and be able to consume *** much air as possible. Thanks for the responses! The adjust-ability of this throttle body and the clean looks are a killer deal for just 430 bucks.

stevieturbo

So there are downsides...and absolutely no positives unless you need something large enough for 2-3000hp

What size boost plumbing are you using ?

Dustin11

That's correct. There are no advantages from a 105mm throttle body. I feel drive ability is better with a smaller throttle body.

I have a 531ci Big Block with a 118mm turbo and use 4" intercooler tubing with a single 90mm throttle body. 4.26 at 175mph in the 1/8 is a 6.60-6.70 at 210+. I have considered swapping to a 105mm but wanted to see just how far a 90mm could go. I have not found the limit of it yet.

Ran 8.90's with a 70mm throttle body also.

LQ4 Tank

It's 3" dual in and 3.5" single out that will run straight up into the throttle body.

stevieturbo

So with a 105 your boost plumbing will throttle the air supply before the....throttle.

See how silly it sounds on that very basic level.

LQ4 Tank

True, I didn't look at it from that perspective. If I ran a larger cold-side out of the intercooler will it help vastly, or no because of the initial choke point being 3.5" coming out?

Dustin11

A 90mm works well with 4" tubing. The 105mm is a little larger then 4". If you run 3.5 from the cooler to the TB you will need a 3.5-4 adapter for either TB. A 4" silicone hose has to be stretched to go around a 105mm TB.

I just did charge tubing on a 540ci twin 76mm street car. He put a 105mm on it and its even overkill for that engine. Twin 3" into a single 4".

stevieturbo

How much power are you expecting to make ?

As said, even a stock 75mm TB has made over 4 figures with no problems, and with 3" pipework

So unless there are an insane amount of bends, the 3.5" pipework will have no issues supporting almost any power that mere mortals with LS engines will make.

So no, having a 3.5" outlet on the cooler and using 4" pipework...almost seems totally pointless unless you were trying to overcome any additional restriction posed by lots of bends.

And even at that is there any point in such a large TB ? None whatsoever.

LQ4 Tank

That's essentially why I started this thread, to find out if it's useable. I want to put 11-1200 to the ground, practically. I wanted the 105mm TB just to know it won't be a restriction, there's not really a price difference so it's not like I'm out anything. But if it's too much throttle body I won't go that route.

stevieturbo

As Dustin says, 90mm will be more than enough....with plenty to spare as far as airflow capacity and will make installation with pipework sizes easier.

There is just no sense whatsoever in going excessively large as all it will do is hurt low speed operation as they simply flow far far too much air per degree of blade opening.

LQ4 Tank

So with the 105 out of the question, is the 90mm the most optimal TB for my setup? It measures just over 3.5" so it would almost match the cold pipe. And then, should I run a 90mm intake as well, or does that really matter? There is no difference in design of the Hi-Rams but the mouth port.

Dustin11

I'd just run the 92mm version. It's still more than enough for your needs but I think the 92 and the 105 are the only options in the hi ram.

LQ4 Tank

Yes, you are correct, they only come in 92-105mm, thanks everyone for all the advise and help!