NEW! StreetRace Billet Intake Manifold from Hahn RaceCraft!

Quote from Flybuddy

Have there been any apple to apple dyno comparisons with this manifold? ie; an existing CAI and free flow exhaust set up where a dyno is done before and after with the only change being the new intake manifold. At 20% the price of boosting IMO it would be nice to see at least 20% of the normal HP increased after boost for a break even on dollars per HP.

We did such back-to-back testing, and saw about a 10 HP max pickup when installing the intake manifold, with greater HP across the powerband, for a maximum of 183 WHP achieved with CAI, exhaust and this intake manifold.

The butt-dyno results so far have also been quite favorable, as @FunCycle attests to above!

A friendly aside: normally aspirated power is always spendier than boost per HP

Quote from FunCycle

All of the problems straightened out, my fault. It is well worth going to this intake manifold. It pulls like crazy all the way from 3,200 rpm to the red line. I have not put many miles on it yet but did do 3 or 4 runs in second, third and fourth from 3,200 rpm to red line.

Thank you for being an early adopter! And also much obliged for the kind words about our product.

Quote from bjk81

I’ve said this before Bill the product looks amazing and really dresses up the engine bay. Be interesting to see the hp difference with a SC. I wish I could of been your test dummy but momma said no. LOL

Thank you! We are working on a supercharging version that uses this intake manifold and our PortFueler EMS. News at 11

Quote from Murder After Midnight

Have you tested with headers yet?

Not yet. Even at 183 WHP, this was still with a stock exhaust manifold and stock PCM tune.

Quote from Murder After Midnight

How does she feel with the stock PCM? How's the IDLE? Is the RPM band smooth? Does it feel like it lost a lot of low end torque?

Stock PCM tune works very well. Idle is as smooth and tight as the stock intake manifold. RPM gain is also smooth, and while low-end torque is somewhat reduced by the shorter runners, the manifold gives back in spades at midrange and high RPM. If anything, the resultant powerband is broader and more usable than the stock manifold, which becomes quite restrictive at higher RPM.

It's key to keep in mind that while the LE9 2.4 Ecotec has been a fine fit for Slingshot, it was originally designed for an automotive application. As such, the GM design objectives were to optimize midrange torque, even at the expense of maximum power, as that's the range a heavier vehicle used primarily for transportation seeks to be best in. In a much lighter, sporting application like Slingshot, we're not as concerned with optimization of that midrange powerband, and can use the benefit of better efficiency at higher RPM quite nicely. As such, the replacement of those long, torquey but restrictive intake runners with our shorter, tapered runners makes a tremendous difference in the engine's personality. With the StreetRace intake manifold, it pulls like a demon all the way to the 6500 RPM redline, rather than basically "falling off the pipe" as the stock intake does above 5000 RPM, where those long runners start to really create drag in the stock manifold. Further, as the Slingshot is also hampered by limited traction, taking some of that meaty midrange torque away makes it easier to get to full throttle without the attendant wheelspin. If anything, the new powerband is more driveable and manageable as a result, more linear without that big "bump" of torque in the midrange....and just more fun!

Of course, another airflow benefit is the new throttle body location. With no 90-degree bend just above the throttle body, instead a straight-through approach directly into it, flow/efficiency at high RPM is also increased.

Quote from lrobbi

Took mines out for a quick ride last week, temperature was just about 48 degrees and the street was cold along with the tires. I was not able to get in on it hard but right away I could tell it was different. For sure more power but I cannot say what in numbers…if I was “butt” dynoing I might say 8 – 10 hp gain but that is just me and it could be greater. I need more time and warmer weather…. I am HAPPY with what I felt for sure. Feeling it pull harder at 3K on up was a nice feeling. (Running DDM Super Charger w/ upgraded smaller pulley x2)

Thanks for the glowing review, and for helping show that this is also a great upgrade to supercharged Slings!

Quote from WraithSS

Just ordered one last night.

Thank you for your order. Yours ships early this coming week, please keep us posted as to results

Another aspect I seem to have noticed is that throttle response also seems quicker and less laggy, which is a sweet upgrade to any electronic throttle system, as they are already a bit slow to respond to fast changes in accelerator pedal. As this is a subjective analysis, I'd like to see what other users of the manifold say. What do you think, @lrobbi? Does it seem to respond more quickly to throttle input?

What would be attributable to this is, of course, the reduced air friction of the shorter, tapered runners and large plenum. There's considerably less inherent drag, delivering an air charge to the cylinders more quickly when the throttle is opened.