Bret, I wasn't saying that Holley, Accel, and Ron's made elbows. I don't know whether they do. I was saying that if hood clearance wasn't an issue, they all make throttle bodies that directly bolt up to a single plane manifold.

 

Yeah, throw Wilson in there as well. They have some of the best made parts I have seen yet. Ron's is up there too.

BTW just had a guy ask me about a HSR for his LT1 in a early Vette... everything work on your setup?

Bret

 

Unfortunately, financial constraints and not enough time did not allow me to do anything but get it installed. However, it is on the motor and in the car and everything works. Winter has arrived in the northeast now, so the race car is in the garage. Hopefully I can get it on the dyno for a retune and to the track once spring gets here.

 

Good just wanted to check in with ya.

Bret

 

Any thoughts on front to rear cylinder imbalance with a forward facing throttle body ? I've got a HSR on a L98 type 398 (.040" over 350 block). After a dyno session I noticed the plugs were rich from the front to lean in the rear. Got me to thinking about trying a single plane intake, or extending the plenum forward.

 

It's funny you should mention that. When I had Bret convert an HSR to work on my LT1, that was a major concern of mine, since the HSR has no IAC channel like the LT1 intake. I expressed that concern here and was told by several people not to worry about it. Unfortunately, I haven't been able to get my car on the Dyno for a tune, so I don't know if it's going to be a problem. Personally, I think it is going to be a problem, and I am also thinking about possibly switching to a single plane in the future. My race car has a Corvette big block style cowl induction hood, and I have cut out part of the cowl, so I should be able to use a four barrel style throttle body without an elbow.

 

Good thing I put the MAP plug in in the middle of the plenum then.

The IAC though can't really do to much about.

Bret

 

I'm curious about this killer short side radius (SSR).

If you have a 4bbl TB on the intake, doesn't the air still have to make a sharp turn to get into the TB (although, the air has the "choice" to come from 360º around the TB)?

How is this bad SSR measured? CFM?

I lost 30rwhp when I pulled off my air filter and let the MAF "dangle" around on the dyno. My guess is that the the extreme suction of air into the TB was intereferred by the perpendicular air "trying" to make an instant 90º at the edge of the MAF. Just a hunch.

Just like Brett's sig: Theory is great and all, but can anyone offer real world advice?

"I don't like it" and "It doesn't look good" scare people into not trying things. Not saying that some caution sholdn't be excercised, but isn't the whole idea of keeping a stock hood a compromise? Heck, the stock motor is a compromise. Life is a compromise.

I'd like to offer some real world numbers as I put together my SP intake (dubbed: project monoplane ) using a little logic, a little theory, and a little dinero. Probably looking at a month before it comes complete, but I promise I won't sell it before I verify it doesn't make any power .

Ryan

 

Just to add a little bit more deductive reasoning...

The stock intake draws air in and the air must make 8 near-90º turns inside the plenum, right? In a single plane, teh air flow is much more gradual and smooth. So, is one single "hard" 90º turn more disruptive to airflow than the LT1 intake?

Runner length aside, a single plane seems like it would "direct" the air much more smoothly after the flange.

So....smoother flow inside the intake, or smoother flow outside the intake? I might be assuming way too much .

Ryan

 

Ryan,

I think you are missing something with how the flow works where it works.

If all the air for the motor is coming over that SSR in the bottom of the elbow then it IS going to have trouble feeding and flowing into the front 4 cylinders.

If you have a better more gradual radius on the SSR then you can feed the front cylinders more and faster.

A sheetmetal intake or a tunnel ram intake like the LT1 basically is, is fed on a 360° area, and one of it's huge drawbacks that causes it to flow badly is the hard radius on 3 sides of the port entry and a non existant one on the shared wall. Just because the air flows in thru that intake does not mean it does it very well. FWIW the air doesn't make a staight line from the TB to the runner and turn 90°.... you need to think of it backwards. The low pressure in the cylinder is sucking air thru the valve, down the port, thru the intake runner, out of the PLENUM, thru the TB and MAF/Aircleaner.... The plenum is basically a storage tank to store air that the cylinders need once the valve opens.

Bret

 

It would be interesting to see what a short height SP, with factory restrictions (TB, stock hood) could make in a street car.

I asked "altjar" what he gained with his swap, but he has not gotten his combo tuned up to where it could be. If everyone that asked the "what LT1 stroker parts work best" question had an idea of all the different crap you have to go through to make a solid motor (that made any power), they would buy an LS1. Most of them will, are, or already have done .

Ryan