Am I crazy? 2.0 LeMans spec.

[trekkor]

I have a 2.0 914-6 short block and a set of 2.0 heads.

Will this case handle the 220hp and 8000rpms I want?

KT

[Brant]

Trekkor,

is it the sand cast from your white car or an actual 914/6 mag block?

The thing is that if you want 220hp your seriously talking about a twin plug 15K engine.

much MUCH more affordable to get the 220hp through displacement, since you are not limited by a racing class.

it can be done through single plug, but race gas only and it will not be long lifed.

I have a friend with a 906spec twin plug in his 914/6
it really is close to that output.
I'd bet that he has 20K into the motor.
you don't want to go there.

brant

[ErVikingo]

I have more than that on my engine, both power and $$$ wise. Its doable but it costs money and a sand cast case would be more appropiate (and cheaper to modify) than the mag one.

[trekkor]

What are the expensive components?

Can the 2.0 heads be machined to accept the big valves?
I have no p/c's, cams

this is a 914-6 case. My current 2.0 S is in the car and running real well.


KT

[tadd]

Titanium rods will set you back 3.5k - assuming you want as close to a C6 as you can get. You can use premium steel rods, but there is a 60% mass difference between Ti and steel. You really want new Ti rods as they do have a fatigue life. Then you need to chase up a set of 69S heads (1k+ anymore?). It's not worth the effort to use 69S valves in a set of 67/68S-69T heads. I looked hard at doing that. Oh, the valves aren't peanuts either. If you can live with the 'sin', use 2.2 heads bored to 38 mm (although folks have used stock 69s porting with only a small loss on top). Supertec even has new 906 clone cylinders that are spiggoted for the larger 2.2 heads. More money in the valve train depending on which way you go. If you stick with the 'olde skool' porsche cams (C6, RSR sprint) then you can use stock stuff cause the ramps are so gentle. If want the last bit of oomph and want all the area under the curve, then you will need uprated springs and ti retainers. Did I mention RSR solid rockers? Don't forget the twin plug (1.5k for the disty and 400 for the machining) as you need all the compression you can muster and the high dome interferes with flame travel. Don't forget all the standard machine work to get it put together.

BTW, your mag case should be just fine. There are plenty of 40 year old race cars with C6 motors still being spun to 8k out there on orginal mag cases. I'm sure this will be a bone of contention, but you really don't need case savers with a 2.0 on a mag case. They just don't get hot enough - especially with all aluminum cylinders. IIRC, Steve@rennsport has said that steel studs are just fine for a 2.0. So that just leaves squirters and oil bypass mod. You would be doing that anyway with an Al block.

tadd

[Brant]

its cheaper to buy and rebuild a set of 69S heads than it will be to machine the bigger valves into your existing heads.

the P's and C's required to get 220hp from a 2.0 are going to be pricey!
(There are some amazing new ones out there starting around 2500)

your going to need aggressive cams

your going to need expensive valve train.

your going to need all of the case mods, rods, and oiling mods to support 8,000 rpm.

basically all of the parts are going to be expensive because your shooting for the upperlimits of what a 2.0 can offer.

I'm trying to do the same right now on a budget
I'm going with 81 P/C's on 2.2 heads with special valves and valve train.
(I'm allowed an overbore of 81mm in my 2.0L class)
I'm really Really trying to do this on a budget.
I only expect to get 200hp and I'm required to stay with a single plug set up in my class. I'm budgeting $6.5K for a top end job with P's and C's.

you could easily double that with your goals, and twin plugs.
twin Electromotives will probably be your cheapest path to a twin plug at another 1500 + machining

it would be cheaper to buy a 3.6L motor
no replacement for displacement.
although I really do love the way a 2.0 revs, unless your class requires a certain displacement its not cost effective when your just trying to gain 40-50hp.

brant

[trekkor]

Here's what i don't understand:
I am getting 150-160hp now. ( my $1500 complete motor )

How will big valves and higher compression cost so much?

Isn't this a $4k project? ( parts and machine work )

I don't know how much to assemble to longblock.


KT

[tadd]

Hp is related to torque and rpm. Torque is related to BMEP. If you want those last 40 hp, you need both. BMEP you get from running the CR as high as you can. There is a big difference in components to spin 7k all day or 8.4k. More RPM allows for more agressive cam timing which leads to needing more valve to take advantage of more flow. Mass needs to be removed from all the rotating parts fo live at higher revs and that costs money in either materials or design.

If it is a street car and you are going to stick with S cams, you might want to consider a 2.1 longstroke (2176 with 81mm pistons actually). You just swap the 66 for a 70.4mm crank. You get better breathing with the smaller valves, 906 CR with S pistons and more bottom end torque with the improved rod length.

tadd

[jluetjen]

KT;
Bigger valves and higher compression are really only to get you the HP bang if you spin the engine faster. HP is a function of how much air/fuel mixture you can combust in your engine in a given amount of time. So the knock-on affects are:

1) Higher rev's, which mean more stresses on the bottom end and valve train. This can often mean a bigger oil pump to keep the sump dry (reducing windage losses and foaming), and to pump that oil "uphill" and maintain pressure all the way through the fast spinning crank in spite of centrifical forces. It also means higher accelerations on the valve train, and more inertia from the larger valves.

2) More heat -- more HP always means more heat. So now also need the bigger pump to ensure adequate flow to all parts of the engine to draw away the heat. It also means more stresses on the individual engine parts.

The neat thing about a 911 motor is that the 3.0 made as much HP as a tightly wound 2.0. So a lot of the oil system modifications made up through the 3.0 or beyond (like a 964 oil pump) will do the job for a full race 2.0. The same applies to many of the other parts with a little creativity. But when it comes to 8000 RPM, you're stuck having to use the good stuff in the bottom end and valve train to support those rev's.

[trekkor]

Good responses and PM's.

I currently turn 7300rpms with my 2.0 S

If I used high comp pistons, did the valve/head work on the 2.0's what kind of hp could I hope for?


Thanks, KT.

[sww914]

Great question, great thread. I wanted to subscribe.
Thanks guys.

[BigD9146gt]

KT,
For what its worth, I just picked up parts engine based out of a '72 2.4 with RSR 2.8 p/c, 908 grind cam for the 911, and a modified MFI pump to match. From all the readings on this board, to go from your 7300 (stock capable) to 8300 (race proven) is the exponential jump in price. Everything doubles as the rule of thumb... it doesn't make sence, only cents.

cheers, don.

[Vintage911Racer]

Call Frank Beck in AZ.. 602-997-6572.

He has more then that running in his 914-6. He has tried many variations.... I know they are not more then 10-15 hour motors before bottom end rebuild.

[Brant]

Trekkor,

mark hit upon an important point.
I'm guessing that most 220hp 2.0 motors are going to last 30-50 hours.

and to be specific about your questions on the big valves in your heads.
the quotes I was getting to use a T head and put big valves into it were running around 1 grand for machine work alone on just the seat installs
brant

[trekkor]

When you say "last". Is that because they broke or they aren't putting out peak power anymore?

30-50 hours could be 2 seasons depending on use.


KT

[Vintage911Racer]

On an average 3 day race weekend you are putting about 6-8 hours on your motor. when you take into consideration warm up time, pre grid time, cool down lap, back to pits etc etc etc... On 2 day weekends just a bit less. then you throw in an eduro or two and Whamm... 30 hours is there before you know it. My last motor went 72 hours before rebuild. that was 2 full seasons. So average 35 hours a season (9 races).

I was running 69 "S" type heads in my 2.0L with large valves in it.. I just sold them and yes, they were expensive to build... But my 2.0L was fast.

Give frank a call.

[trekkor]

I don't understand the significance the "hours".

They wear out that fast?


KT

[Brant]

Originally posted by trekkor
When you say "last". Is that because they broke or they aren't putting out peak power anymore?
30-50 hours could be 2 seasons depending on use.
KT

I think the problem with how long will they last ?

is that at that kind of tolerance and build up it will cost 2x as much to let the motor die... as it would to tear it down and freshen.

so regardless of peak power, a motor like that has to come apart and be freshened regularly...

brant

[Brant]

Originally posted by trekkor
I don't understand the significance the "hours".
They wear out that fast?
KT

when strung tight enough to produce 220+ hp..
yes they tend to wear out at 8500rpm
and then bam, bang, and things will get expensive all over again.

so they get rebuilt per number of hours to avoid failure.

hey I sent you a PM this morning.
shoot me an email direct
brant914@hotmail.com

[trekkor]

So, it sounds like it is a very expensive motor for a non-race application or hobby driver.

Disappointing.

How do S2000's run at 9k rpms and last?


KT