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Old 03-30-2008, 02:15 AM   #1
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Lightbulb 350whp On A Stock Shortblock?

I know, I know, the common wisdom amongst my fellow mt.net'ers is 250whp is safe with a good safe tune. Some have pushed that and been successful. (Paul, Y8s, Ben, and I know there are others, please chime in!) I just keep thinking that I could make 350whp or so on a stock shortblock. I have a 99 engine. The head isn't stock, it's been pretty modified to enhance flow, more so than most heads are done. This should help to keep boost down and flow up, which is important for my SC setup especially.

Anyway, I'll have a shitload of flow available from the two SC's. Well, I can pump 800 CFM quite efficiently. Anyway, using a 4.4" crank pulley was the original plan which would be around 440CFM at 7K engine speed. I figure that would make around 300whp. If I go to a 5" crank pulley, I would be pumping 530-560CFM, give or take (I haven't done this calculation, this is a rough estimate).

The motor will have a custom header with huge primaries and a custom intake manifold as well. Everything to support the power will be done right the first time, but the engine itself internally is stock. I'll have a huge intercooler (18-22"x12"x3" core demensions) and water injection. The tune will be VERY conservative.

It's my speculation that the motor would make this kind of power on stock internals. 300whp isn't what kills the motor, it's 300whp with any hint of detonation. The fate of the engine will more so be determined by the tune, no so much by whether it's making 300whp or 350whp. I do realize it has it's limits, but would the rods just fold under this much torque, would the ring landings break at these levels? I think not, am I wrong?

I could also implement EBC pretty easily too, using the bypass valves to act as a wastegate to limit or turn off boost. That way, I'm not making 350whp every time I redline it, but only on occasion. Perhaps I'll have a switch for 15PSI with EBC. Turn it off and I can make big power.

So, good safe CONSERVATIVE tune, conservative redline (7k max), big IC, WI, healthy fuel and cooling systems, custom header and intake manifold, EBC, etc, is 350whp realistic? I'm talking about going 15K miles and one year before I rebuild it. Motor is very healthy and strong right now and just rolled 140K.
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Old 03-30-2008, 02:19 AM   #2
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are the stock rods forged? also i agree with what you said with detonation, but would two superchargers = one turbo heat production wise?
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Old 03-30-2008, 02:24 AM   #3
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Stock rods and crank are forged, pistons are hyper... something. There are people building 400whp engines with stock factory pistons, so I don't see that being the problem. It's heat and detonation that kills them. Stock rods are forged, but the rod cap bolts are the weak spot. IMO, HP isn't gonna cause that to fail. It's high RPM's when the piston moves past TDC on the exhaust stroke that stretches on those bolts. Limiting RPM will save them IMO.

EDIT: there will be heat from the SC's, the charge air will be hot for sure. Good thing with the twin screws is they are more efficient than a roots, so as snout speed goes up, charge temps are falling, not rising at any given pressure ratio. With the IC I can probably get charge temps within 25*F of ambient or better, and I'll have WI and a huge water tank in the trunk. I plan to use water liberally.
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Old 03-30-2008, 02:37 AM   #4
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true dat, water will be good, didn't know that about the superchargers though, never researched them that much. Figured if this audi r8 i'm racing with is good enough for turbos then so is my miata (damn toyota 88c-v)
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Old 03-30-2008, 09:24 AM   #5
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There is a guy local to me who's been running a stock 1.8 with a TC61 at over 300whp for a year. Careful tuning and good engine management are key. He's got one of the TEC standalone, a III I think, though I don't recall exactly (it's not one of the newest ones). He's broken pretty much everything but his motor. But I fear that a rod pretzel is imminent.

For the s, please understand we're talking about the exception to the rule here. Don't try it at home kids.
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Old 03-30-2008, 10:33 AM   #6
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IIRC, Ric was making 400HP on his stock block(s) in his attempts at the 1/4 mile. There was VIDs somewhere at one time..
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Old 03-30-2008, 11:37 AM   #7
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on the 9:1 compression motors it's probably a little safer. if you're doing it on a stock 99, you've got half a point more compression to deal with.
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Old 03-30-2008, 01:36 PM   #8
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Quote:
Originally Posted by y8s View Post
on the 9:1 compression motors it's probably a little safer. if you're doing it on a stock 99, you've got half a point more compression to deal with.
True, but I removed a lot of material when ushrouding the valves. It was enough to drop compression at least a 1/2 point, if not a full point. That should help a little. Hell, I'm almost positive it was enough to drop compression a full point.

Ben, that's good to hear. Do you know if he's running a 99 shortblock or a 99 head? The rods would be the weakpoint I believe. Any detonation at these levels would probably fold them. I agree that tuning make the difference at these levels. However, looking at all the people that do pop stock motors, I always see cracked pistons and broken ring landings, not pretzeled rods. Most of the damages are from detonation, but it really makes me wonder.

FWIW, I had a nitrous problem one day and sprayed a 100 shot at 900 RPMs. It blew the hell out of the head gasket but never hurt the rods. Motor was making around 600 ft/lbs of torque at 900 RPMs for a second till it jumped to 6K.

Jefe, who's this Ric guy? Is he a member here? Did he daily drive his car?
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Old 04-28-2011, 01:37 AM   #9
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**** me for bringin that back to life, was searching and didnt pay attention to the date.
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Old 04-28-2011, 01:43 AM   #10
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Old 04-28-2011, 02:12 AM   #11
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Remind me - Why did we ban Pat, again?

Seems like he has some cool ideas.
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Old 04-28-2011, 03:21 AM   #12
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Pat was chirpin' Rick. That doesn't fly.
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Old 04-28-2011, 03:30 AM   #13
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Pissed off Rick.

Plus he's a moron.
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Old 04-28-2011, 04:12 AM   #14
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Gotcha.
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Old 04-28-2011, 09:30 AM   #15
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Pat tried to stage a coup.
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Old 04-28-2011, 10:37 AM   #16
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Pats a pp
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Old 04-28-2011, 07:11 PM   #17
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Quote:
Originally Posted by Braineack View Post
Pat tried to stage a coup.
How is that?
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