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Icy Hot Stunta
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Discussion Starter · #1 ·
Did some more screwing around trying to make lots of bolt on hp and found a new sweet combo.

I got 170 whp and around 140 soming lb/ft of torque with bolt ons with a nice broad useable powerband, more power everywhere in the powerband from 2000 rpm up than your typical S4 bolt on motor. This is nice fat useable power that would be ok on a street car sort of if you could stand a rocking idle thats steady and stall free at 1400-1500 rpm. I belive this is a bolt on power record and should soon be obtainable soon by nearly anyone.

This is pretty cool, this is more power and way more torque with a wider powerband than the fabled Intergra Type R and modded B series motors. This is also better than most internaly modifed SR20's. The gains come from some of the discoveries made lately.

The engine is a old SR20DE with so so leakdown, at 5-6 percent, its not the freshest motor as many old SR's leak down at 2% or less so this should be easly reproduceable. The engine has JWT C3 cams, valve springs and adjustable timing gears, Hotshot CAI, Unorthadox UD pulleys, Hotshot Gen 6 headers to a 3" exhaust and a JWT ECU.

The lobe centers are adjusted very tight with lots of overlap neccesitating a big exhaust and header collector. This has been proven as the hot SR tip by our latest experiments. The intake cam is advanced 7 degrees and the exhaust retarded 7 degrees which is the very limit that the stock engine can take. The engine my like an even further spread of the lobe centers as the powerband kept getting wider and fatter, but piston to valve contact will occur. For those of you who have C series cams, get a big collector header and exhaust and tighten up those lobe centers. You can gain 10-15 hp in the midrange.

The ECU was the standard S4 JWT program and no gains were to be found by adittional tuning. The base idle was raised to 1500 rpm in the idle program to help stabilize the idle. The rev limit was rasied to 8000 rpm. Interestinly enough, the bigger the cams, the less sensitve the SR is to fuel ratio. Milder motors like to be run as lean as 13.3:1 for best power but with big cams, the motor makes the same power from 12.6-13.3:1! Better to tune to the conservative side in this case.

This is the same engine that the S5 cams were tested on. Surprisingly the S5's made nearly as much peak power and the C3's. Where the C3's shine is there much wider powerband and exceptional torque. Except for the idle, the C3's are actualy better street cams!

Also tested lately were a 70mm N-1 throttle body, cobra MAF and several iterations of intake manifold. For a NA motor, we may prove that the STOCK manifold is the best choice. We built a trick veriable plenum manifold and managed to gain slightly more peak power at the expense of some midrange. The throttle body and MAF make no difference in power which is good, money you don't need to spend!

Because we can't find much gain with a manifold, it looks like the low 170's is going to be the limit for bolt on power. The good news is that the tuning is easy, I documenteded it hear and anyone can duplicate it. Very few NA 4 cylinders can claim anywhere close to this power and torque with bolt ons and only the B and K series Honda motors can surpass it.

Follow the recpie and reap the benifits of hundereds of dyno pulls! Good low buck hunting!

Mike
 

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morepower2 said:
Also tested lately were a 70mm N-1 throttle body, cobra MAF and several iterations of intake manifold. For a NA motor, we may prove that the STOCK manifold is the best choice. We built a trick veriable plenum manifold and managed to gain slightly more peak power at the expense of some midrange. The throttle body and MAF make no difference in power which is good, money you don't need to spend!

Mike
Out of all the great information you've posted, Mike, I find that to really be the most interesting... I know, I'm a bit odd. It's not always about spending less money or even using "cheaper" parts... not spending any money for "improvements" is very cool.

Peace,
Mark
 

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Icy Hot Stunta
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2,366 Posts
Discussion Starter · #4 ·
darkelf said:
wouldnt the 70mm throttle body make it more responsive though? Not talking power but eagerness to rev.
Yes but a bored out stock TB is easier to mount and makes the same difference in throttle response. A 70 mm requires welding and porting of the manifold.

Mike
 
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