300 BHP 3.0 litre

[ix0ifan]

If we started with a 3.0litre 911SC Motor (180BHP) what do you think we would need to do to get 300BHP?

I would like to use an MFI and Twin Plugs as we would need to stick to a Spec similar to a 3.0RS Motor.

I don't think we can afford a High Butterfly system.

Can we rev to 8000rpm with standard type rockers? and would I need steel rods such as Carillo?

I have a 2.0 litre S MFI as a core or is this completely the wrong direction.

All ideas gratefully received

[kenikh]

A naturally aspirated 300 HP 3 liter will take a LOT of money. The most important things will be fancy heads like from Xtreme to get the air flowing well, BIG cams like GE100s, ITB EFI wouldn't hurt and most importantly, a bottom end that will take the beating of revving this motor to 8000 RPM.

Forged rockers are a good idea for 8000 RPM - I have a set for sale and not too expensive at $325 for all 12. PM me if interested.

The 'S' MFI as a core is nice and very doable, but you will need to do a lot of machine work to get the stacks opened up. Seriously, you are better off going with EFI unless you have a nut for MFI.

[Steve@Rennsport]

Originally Posted by ix0ifan

If we started with a 3.0litre 911SC Motor (180BHP) what do you think we would need to do to get 300BHP?

I would like to use an MFI and Twin Plugs as we would need to stick to a Spec similar to a 3.0RS Motor.

I don't think we can afford a High Butterfly system.

Can we rev to 8000rpm with standard type rockers? and would I need steel rods such as Carillo?

I have a 2.0 litre S MFI as a core or is this completely the wrong direction.

All ideas gratefully received

Having done a few of these things, I'd offer,

Your 2.0 engine is not a feasible core for this build.

The SC engine can work but as Kenik said, you need different heads. Extreme heads are one choice as would be 935 heads. Furthermore, you will need a CR above 11.5:1, and some good cams that run to 8200.

Any rocker will work but I'd be using the 9Meister ones, now (not cheap).

Street MFI, in any size, will not support 300HP, especially using the cams required for that power level. You need either 46mm carbs, tall butterfly intakes, slide-valves, or an EFI setup using ITB's.

Carrillo or Pauter rods are mandatory as are a whole host of oiling modifications for the engine to live at high RPM.

JMHO, of course.

[kenikh]

I missed the part about using a 2 liter as a core - I thought this was referring to the MFI. You will need to buy a core SC motor. You could manage the 11.5:1 CR w/ a J&S knock management kit to run pump gas, but the heads are the bugaboo. Xtreme heads or some small port SC heads machined by Steve would be a must.

Steve is also right on the street MFI not supporting 300HP, but a properly modified MFI system (pump adjustment, stacks bored with a 52mm>41mm taper) would do just fine. Slides would be ideal for eeking out the last few top end HP, but you could probably get 300 crank HP using butterflies.

The thing I missed which is probably the most important is rods. SC rods suck. You'd need Pankl GT3 rods, Carillos, R&Rs, etc to make sure things don't let go at revs.

Then of course there is the oiling - budget for a 930 or GT3 oil pump, cross-drilling your crank, modifying your oil tank for extra capacity, baffling and larger fittings, to make sure your engine doesn't starve.

Building the motor yourself would save some money, but in parts alone, you could get in over $25K on a build like this.

A cheaper 300HP would be a 930 motor...

[MBEngineering]

HI ix0ifan
this from the customer , rolling road test at @290/295 bhp but most of the rolling roads over hear do not read the same BHP from one to the other, the only thing is the engine was up graded and put back on the same rolling road for the readings;






based on a 3.0 Lt Carrera engine

regards mike

[ix0ifan]

I have an SC Core already and it is running on PMO 46IDA carbs.

It is Twin Plugged with a Marelli Distributor, 10.5:1 German Pistons, GE40 Cams, shot peened rods, GT3R Oil Pump.

It hasn't been boat tailed or half mooned. Heads are SC and have been ported but valve sizes are standard.

It revs to 7200 and has good mid abnd torque from about 2500rpm.

I understood that the 2.0 litre MFI Pump was a good core to produce a pump with an RSR type space cam but don't know much more.

I understand the arguments about EFI but I need to stick to MFI because of class rules.

I thought the 3.0 litre RSR gave 330BHP so would I be better off with a Carrera 3.0 case, heads and a 6 bolt crank?

I had hoped that using the street MFI would be better than 46PMO's but I guess this is wrong.

All very interesting though.

[Steve@Rennsport]

Originally Posted by ix0ifan

I thought the 3.0 litre RSR gave 330BHP so would I be better off with a Carrera 3.0 case, heads and a 6 bolt crank?

There is a huge difference between the 3.0 RSR and Carrera 3.0 engines,.... That said, your SC core is a great place to begin.

I had hoped that using the street MFI would be better than 46PMO's but I guess this is wrong.

Nossir,.....street MFI throttles are positioned much too low to properly contain the reversion issues from using long-duration cams. Thats a major loss of mid-range torque and power.

Many folks "diss" carburetors but your PMO's can be made to work VERY well.

With 42mm venturies, these flow a lot of air.

[bob barnes]

Question? I Had a conversation with a Vintage Racer who also visits this site often and he wonders in today's economy what $$ would it take in parts and mods to build a 280HP engine on a 3.0 Core Motor.

He already has the High Butterfly Injection and Twin-Plug Distributor:

What has been the experience of the other Pelicans who have tried to build themselves a 2.8L or 3.0L High RPM Race Motor? How much more in additional parts required using the 3.0L pieces as a base? I gave him my opinion, but he suggest asking you fellows also.

Bob

[Jimmy18E]

In my humble opion it should be easy (But Spendy) to hit 300 BHP with a 3 LTR. My 2.5SS hit 241 RWHP (Over 300 at the Fly Wheel)on a dynapak dyno, wont even mention what a DynoJet registered. Yes, I have all the goodies, Pauter worked crank, Pauter Rods, DC-62s, Extreme Heads, GT3 Oil Pump, 901 Shop Headers, etc and yes 46 PMOs, no FI.

So yes in my opinion 300 BHP with a 3.) LTR is very possible.

Jimmy

[bob barnes]

Jimmy,

I agree with you. I have one that makes 300HP@the flywheel with 46IDA's. The question is how much will it cost today to build a 300HP long block, assuming you have the proper injection?

Bob

[sc_rufctr]

I've always wanted to build a 300 hp 3.0 liter 911engine.

It's doable but increasing the swept volume is the most reliable way of gaining that extra HP.
But the challenge of getting 100 hp for ever liter would be the thing for me.

I have an 82 motor sitting on a pallet in my garage... Hmmm...

[neilca]

A guy on this board built one. His name is Gert, try the search. He did alot of head work. There is a post were he well documented everything.

[MBruns]

I helped with his project and did the dyno and tune for him, making 300 hp is not all that hard with the right combination, the trick is doing what is needed in the bottom end to make it live, with modified OEM heads we can make 350 to 355 consistantly, the next 25 to 30 require the Xtreme heads, we have 3 out there making 380hp and without mistakes race 40 hrs plus between freshenups. And that is with PMO 50's and a distributor.

Mike Bruns JBRacng.com

[78_Targa]

At what point does the law of diminishing returns come into play? Does it cost 2X to achieve 300HP as it does 280HP. How much $$ and what is required to achieve 280HP, same question for 300HP?

A list, in order, would be useful. Is that unrealistic?

Mark
(stock 3.0)

[bob barnes]

Mike,

I have not spoken to you since you helped me out with that 87.5MM Cyl. for my ST motor.

I know about the bottom-end mods you are referring to. I have it for my 3.6L Race Motor.

The question I wanted answered for my friend-(I have my own opinion of cost) was an estimation for the 100HP/L 2.8L-3.0L long block cost? All of mine had 100HP/L; 2380cc, 2.7L, 3.0L, 3.2L, 3.4L, and my 3.6L. He needs to see it from you guys because he isn't knowledgable of the true cost to attain the results for a true race motor. Each build is different, but how about an estimate of a 100HP/L long block with a Al. SC/Turbo case for a 2.8-3.0L?

Mark,

This build that Mike help with has all the pieces. The question is how much????smiles

Bob

[MBruns]

Hi Bob,good to hear from you, with regards to cost of doing a first class build its all over 20 to 25k if you have a good core to start with for a long block race engine, thats figuring new parts, pistons,rods,cams, full head work,all machine work, big pump,on and on. If you are able to properly assemble and set up all the critical stuff yourself it has about a 5k reduction on the project. then carbs,pipes,ignition systems theres another 10k. Its not a cheap project.

Hope this helps, Mike Bruns

[bob barnes]

Thanks Mike,

You are right on target. I just wanted my friend to see someone else state the true cost of a Race Engine that can deliver 100HP/l and be reliable.

Bob

[2000wrx]

^^^^ Shhhh don't tell Honda.

[Shoepop]

Originally Posted by 2000wrx

^^^^ Shhhh don't tell Honda.

And you got a new car with the engine for 25K.