stevieturbo

And there are many builds with stock LS1 intakes and impressive results. Perhaps even more impressive than any HiRam's simply because it's a stock intake.

A generic statement like that is meaningless really though.

What is needed is back to back tests with various combo's to see the effects the intake change has in the real world, on real builds. Where power/torque differs throughout the rpm range etc.

00Wildcat

We've been 8.9@150 with the Mid-Rise 1.5" 417 Motorsports intercooler and S400 cast 80mm on 23#, 3400#+ 5.3 stock 799 heads 219/223 cam. So the mid-rise sucks.

Multipiece Holley style intakes will not blow part at high boost, I run mine at over 35#. I would venture to say that a TBSS/late truck intake will make as much or more power than any aftermarket intake

SLOW SEDAN

iTrader: (13)

The mid-rise does come in lower then the hi-ram or pro-flo and gains next to nothing over the truck intake. Looks like you are giving up a solid 25+hp to either of the higher cast intakes. Looks like the truck intake gains some lower end torque but I don't think matters much for a car that doesn't see much under 6000RPM going down the track.

OEM TBSS manifold results:
Peak Power: 562 hp at 7,000 rpm
Peak Torque: 497 lb-ft at 5,000 rpm

Mid-ram results:
Peak Power: 566 hp at 7,000 rpm
Peak Torque: 469 lb-ft at 5,300 rpm

Edelbrock Pro-flow results:
Peak Power: 593 hp at 7,000 rpm
Peak Torque: 474 lb-ft at 5,700 rpm

Holley Hi-ram results:
Peak Power: 597 hp at 7,100 rpm
Peak Torque: 474 lb-ft at 5,300 rpm


Those results along with many other turbo car dynos I've seen pickup 30+whp swapping to a hi-ram style intake was enough for me to buy one. I'm going from the lowly old style truck manifold to a Pro-Flow, I'll post results once I make a hit with it.

Martin Smallwood

iTrader: (2)

I'm not as much of a fan of the mid-ram as I am the high-ram due to the lower that Holley uses with the mid-ram. I wish Holley had just taken the lower from the high-ram and lopped off a few inches of runner length instead of using a dual plane lower with dual quad four barrel flanges.

That said I am a big fan of the TBSS intake as it produces a very broad power curve, although the high ram does out muscle it at higher RPM's. Most stock bottom end engines aren't going to be able to utilize peak HP coming in at 7,000rpm as that would require at least a 7500rpm shift point to fully utilize that power band.

Now, if you have a built bottom end and the valve-train to work with a 7500rpm+ shift point and don't mind turning that kind of RPM's, go with the High Ram.

00Wildcat

I'd like to see the same manifolds tested at 10, 15, 20, 25, 30, etc... # of positive manifold pressure. I have a hard time accepting that all will perform in similar manors having air blown through them vs sucked through.

Martin Smallwood

iTrader: (2)

Flow only occurs if there is a pressure differential present. High pressure always travels to areas of low pressure.

In a N/A engine there is a pressure differential that is created via piston motion, resonance tuning from the induction system and resonance tuning from the scavenging effects of exhaust harmonics.

In a boosted engine that pressure differential is still present that allows flow to occur due to increased manifold pressure, just at a greater pressure delta. It occurs as soon as the intake valve opens unless exhaust gas back pressure that is higher than intake pressure is present in which flow still occurs, it is just going the wrong way from where we want it to go.

The blown through versus sucked through analogy doesn't really work like most people think it does. Flow = pressure differential from high to low.

It is true though that with a boosted engine mass flow is greatly increased which changes the amount of inertia that the intake charge has. This is what needs to be modeled IMO when comparing intake manifolds on a boosted engine compared to a N/A engine as it changes how long cylinder filling occurs while the piston is on the compression stroke. Which the compression stroke is when the intake valve closes and traps the charge in the cylinder. The goal is to close the intake valve right as cylinder pressure overcomes charge inertia or else flow will occur backwards out of the still open intake valve.

SLOW SEDAN

iTrader: (13)

On 25lbs boost from an 88mm Holley had to add 25-50lbs of fuel from 5200-6500 RPM for the Edelbrock Pro-Flow compared to the truck manifold. I'd say that's a nice little gain! Probably need even more fuel when I rev it out further.