Cold_B

I have a new 396 rated at 520 flywheel horsepower motor that should be in my car and up and running in a few days. My engine builder suggested that I run a 58mm throttle body, to get the most from it.

I've been looking at the Arizona Speed and Marine 58mm's, and I have a some questions. Would a mono throttle body effect the way a car drives on the street? The intake has already been matched for a 58mm throttle body.

What is the accepted average for cfm vs hp? I've found a company online, and they recommend 2.2 cfm per hp.
The 58mm twin flows 1050cfm which would equal 477hp given that equation.
A 58mm mono flows 1300cfm which would equal 590hp given that equation.

My engine, sits right between the two. I want my car to be completely streetable, so I will probably get the twin. But I wanted to know, whats the rule of thumb here?

rickneworleansla

Did you buy that engine or build it? I'd like to hear more about it if there is another post on it. When I redo my bottom end I may go with a 396 shortblock. Do a search for monoblade in the C4 forums. There were a few guys with forced induction that had some problems with the monoblades sticking.\

Edit: Here is one of them. http://forums.corvetteforum.com/show...ight=monoblade

Bad Karma

I'm confused, a single 58mm opening flows more air than two 58mm openings? Or an I misunderstanding?

CORKVETTE1

in my opnion you can not over throtle body a fuel injected motor i have a 1300 cfm mono blade on my 355 right now and it runs fine

Cold_B

I bought it. Its a Golen Engine 396 Long block.

My Engine

Short Blocks

I did a few searches last night, and all I could find on the subject was those forced induction guys. It seems to only happen to boosted cars.

Cold_B

Here is the monobody.





Here is the normal throttle body.




The normal throttle body has a seperator in the middle. I believe the 58mm is the width of the circle whole in the throttle body.

rickneworleansla

Thats the exact engine I've been over. The all forged 396 for 3.8k shortblock actually. Please, let me know how it runs. Whenever my engine decides to go I'll be doin the same. Do you plan on spraying it also? First I'm gonna go with a LE2/LE3 package from Lloyd Elliott on my current setup. I'm not sure how or if stock ported heads would work on that 396 shortblock though. Or how they would compare to the trickflow.

Cold_B

Ok. That's what I've been wanting to hear. Does it idle fine? Would you be able to modulate it enough to drive in stop and go traffic and from stop light to stop light? That's my biggest concern. I'm afraid it would be so big it would be more like a on off switch than a dial.

Cold_B

I know! I couldn't decide for quite a while. It's alot of money, but he's made quite a few of them, and even has on in his personal camero, so he's knows alot about. That was one of the biggest factors.

Did you read the GM High-Tech Performance article about it? Its August 2006. His car dynoed fairly low, but he has an auto with a big stall in it. The engine itself made the correct power on the dyno.

I can't wait to get my car back. Its been over 2 months since I last drove her!

rickneworleansla

I'll look for the article. Let me know how you like it. I'm jealous.

CORKVETTE1

it idles fine i can not tell it from the stock one in everyday driving

BlackC6LS3

Bigger TB's do not affect the car in terms of streetablility. I picked up a brand new 58mm tb for the price of what people wanted for a used 48mm for my 305 TPI Trans Am and you cannot tell the difference between the two other that it is a lot smoother and it does not stick like the worn out stocker. I set the idle, then the TPS and was off.

I have an ASM monoblade going on the 396 I will be building. If spending the money, do it once, and do it right.

anesthes

I've run a bunch of different combinations. the smoothest and fasted combo was a singleplane manifold, with a LS1 style 80MM throttle body.
To give you an idea on power, that engine was a 355cid in a 3600lbs fbody and trapped 119-120mph every pass. Not as fast as Corky's car, but it was still fun to drive and VERY streetable. (it even passed Mass dyno emissions).

I also ran a singleplane holley manifold with a 4bbl 1,000CFM throttle body with progressive linkage. I wasn't too impressed with how that responded. I like the monoblades, and I'd probably have run one if my current engine needed it. I'm running a twin 58MM right now.

-- Joe

LT4POWR

mono vs 52mm, I'm running a mono on my 350ci LT4, overkill "yes", but I got it planning for the future

tjwong

On problem I can tell you about using these monoblades. If you are using it on a LTx engine with a stock LTx manifold. You will loose the dedicated IDLE AIR passage that directs dedicated idle air from the IAC motor to each port. If you look at the pictures above, notice on the stock TB that there is a third triangular passage between the two main throttle bores. That is the idle air passage. There is a mating hole in the intake for this passage, that passage is linked to a internal set of passages that directs idle air to each individual port. This is that the engine gets idle air directly from the IAC for idle stability. If you loose this, you will get split fuel trims at idle and even at low part throttle conditions. Which will cause some drivability issues in the low end. Depending on what cam is in the engine this can be a problem or not.

Cold_B

Isnt that an IAC on the bottom of the 58mm mono in the picture LT4PWR posted?

AKS Racing

Yes there is an IAC passage machined into the floor of the MB. But if running a factory type intake, there is now way to direct that air back to the transfer port for the runners. It makes it more difficult to tune for driveability.

I own two of these units, and yes I have had lots of issues with the large blade (acting like the wing of an airplane) hanging open. The tuning issue can be handled fairly easily if you are running either a C3SP or a MRII and aftermarket tuning. If you have this stuff you will be fine.

Aaron