700bhp Lump Possible?
 

Hi Scooby folks,

I am new to this forum as well as to the world of Subarus. For a race car project I am on the search for a compact turbo engine with a low center of gravity. So I thought, a Subaru one might be an option. Now the question (please don't beat me up verbally): Is it possible to get a reliable 700 - 750 bhp out of this engines? If so, which type (out of which car) would I need? And: Can you recommend any (professional) engine builders, that have experience with such crazy thing? Would be great if you could help, guys.

Cheers,
Prospero

Cheers mate for the swift reply! Well, it's going to be a silhouette race car, hybrid steel space frame/carbon fiber chassis. 680 kilograms including driver and fuel.

How about the drag strip guys: What power do they run?
(Since coming from the blue ovals world (where our old cossies do around 600) I was hoping 650 - 700 bhp might be possible with the more modern Scooby engine.)

Roger Clark
Engine tuner
As performance
Lateral performance

This is copied from 22B forum. It won't answer your question about power output numbers, but you can judge what these cars are producing in terms of BHP from the times achieved with a scooby 4 cylinder engine.

Steve SMG 8.66 @ 157mph - 2.5L blue GC8 SMG Tuning - Rigolli 4wd auto
Mikee Singh 8.83 @ 160mph 2.0l White/Orange GC8, Scoobyclinic - PAR
5 speed dog
Andy Forrest 8.87 @ 164mph - 2.4L Blue/White GC8, AFP - 5 speed dog
Steven Darley 8.95 @ 168mph - 2.3L Yellow GC8, Lateral Performance -
Modena sequential
Olly Clark 9.23 @ 148mph - 2.0L White GC8, Roger Clark Motorsport -
RCM sequential
Clive Fulcher 9.36 @ 151mph 2.3L Blue GC8, Mad Hammer Motorsport -
Samsonas 6 speed dog
Gulli Halldorsson 9.48 @ 151mph - 2.0L White GDB, Team Ice - RCM sequential
Paul Blamire 9.63 @ 154mph - 2.3L Blue GC8, Zen performance - PPG 5 speed dog
Jan Frank de Wagt 9.90 @ 142mph - 2.3L Blue GC8, Scoobyfreak Tuning -
PPG 5 speed dog
Mikee Singh 9.91 @ 132mph - 2.3L White/Pink GC8, Scoobyclinic - 5 speed syncr

If you enter the relevant stats here http://www.torquestats.com/modified/...pid=calculator it will give you a good idea of what power is required to hit these numbers, and 700bhp probably won't cut it in a 1000kg car! :D

As for reliability, forget it. Engines running at these extremes will be fine until they break, and they all do from time to time.

And your list of top engine builders should include Finch Motorsport.

Rocko is running 700+ on a 2.1 advanced automotive built engine with a GT35 iirc, and it's seen track days so it is possible ;)

lateral performance banana car is running a custom 2.35 stroker engine internals and is pushing close to 750 bhp. http://lateralperformance.co.uk/ there reputation speaks for its self :thumb:

Yes it can be done 2.35L is the way to go, they can be reliable to if done correctly :)

Mike when you say reliable, what does that mean in terms of track time. Let's say 5 meetings per year and 10 runs/meet. What would be the maintenance requirement on a 750bhp 2.35 lump to run that kind of duty reliably?

Miles completed on that engine ? ;)

I'll let Mike answer the reliability question above, but just as a bit of quick guidance - the 2.35 referred to uses the closed deck block EJ22T block (2.2 litre set up normally) with a 2.5 crank from the later larger engine to produce a stroker engine with a 2.35litre end result.

The benefits of this set up is the 2.2 block is allegedly the toughest block out there - different casting method, thicker cylinder liners, so when built up is the best hybrid of the larger capacity CC for more torque, still good revvability and unburstable (normally) nature.

I run a 2.35 with a GT35r without the variable valve AVCS set up (which would give even better results if I had it) and on straight V power at 2 bar it makes around 580bhp/480ftlb. This is on a road car. With Meths or race fuel, plus AVCS - 700 would be in reach IMHO.

Depending on your application there are also other alternatives

- speak to Alyn at AS performance ("Stockcar" on here) - he makes an CNC insert to convert the weaker newer semi closed deck 2.5 blocks into closed deck blocks (although the cylinder liners are allegedly not as strong as the ones in the 2.2 block) and they run big figures with high torque.
- for the real McCoy, some people have started using the flat 6 block from the older SVX models and adding all the newer valve train / head etc knowledge from the 4 cylinder. As one example, Andy Forrest Performance has the fastest manual subaru in the world 1/4 mile 8.2 seconds at 175mph and he also circuit races it. He has a 3.6 ( stroked 3.3) with twin turbos in his classic subaru and it is rumoured to run anywhere between 1000 and 1200 although exact figures are not released. another example is Jolly Green Giant both he and Andy F post on here and on the more tech focussed 22B.com. They have posted build threads as well.

The scooby 6 cylinder is still light and has a low CoG - very like a Porsche flat 6 (and even sounds a bit like one )

Hard to say mine has done 15 track days, 4 years and 28k miles, just oil changes and regular map checks by Simon JGM

Push to 750 and head gaskets may become an issue. I have stuck around the 700 and seem to have found a sweet spot :)

Dry sump is a must IMHO

Yep I think most would call that reliable. Thanks for the info. :thumb:

I like the 2.35 but always find it hard to justify the extra expense of the EJ22CDB block over the every bit as reliable EJ20CDB.

All those cars listed above only do limited mileage though.

Other question is why 700bhp though?

Its not what it does mileage wise, its what it does at full throttle that needs monitoring closely, especially extended full throttle, where oil temp rises.
Its a different engine requirement from trackdays @ 700hp, to a race car inviroment that is running flat out for 40 to 50 minutes, circuit dependent, but somewhere like Silverstone GP circuit is a very harsh inviroment, compared to say Cadwell or Mallory for full throttle conditions.

True enough but when you look at the OP's spec below, would you really expect that car to see many road miles?



Well you have to start somewhere don't you? ;)

depends on your definition of reliable :thumb:

Shouldn't you also find out from the OP what kind of budget he has to play with to hit the 700+ they're after.

The more they have to play with surely the more changes can be done to get the right level of performance and reliability.

I'd always go with calling a specialist and having an old fashioned conversation rather than letting the internet answer! Fortunately no trolls have got hold of this one yet though.

It's done just shy of 15k now

👍

http://www.advancedautomotives.com/subaru-impreza-21-forged-cdb-shortmotor-engine-package-757-bhp-644ftlb-1480-p.asp


You might want to have a nose
👍

:D

not sure why the page says 757 but then the youtobe vid it links is only 615 :S

The difference with race fuel

I know this is an old thread, so will just leave this here.


The Chevron Motorsport / JC Racing Subaru 2.1L that just won this years Club Time Attack 4WD runs somewhere in the region of 750bhp / 750 FT-Lbs TQ on race fuel using a OD special GT35. It was raced hard all season so Chevron can definitely build you a reliable engine that holds that power.


Speak to Simon@Chevron Motorsport UK.

it wont have seen much time at full chat though, one lap circa 2 miles, then back off, 10 events, so done 20 miles at full chat. i wouldn't say thats a bench mark.

Best example i can think of is vaughan fletchers classic thunder race car to full MSA sealed block spec, so no rebuilds mid season. Does 20-30 mins absolute flat out at each race and last engine lasted a few seasons. it's runnign circa 725bhp.

An example of some hammer ;)

Higgins 2017 Isle of Man TT car was circa 600bhp and I'd say that was reliable flat out. It was far from standard though.

also due a strip and rebuild in less than 1000km tho

Oh yes totally agree, but for an all out race car that's actually very good really.

50 miles and rebuild, it went back to the factory and was rebuilt after the event. Same as all the factory cars.

MSA events run multi races on same engine so i wouldn;t says its very good at all