Stock, stroker or ghetto capacity increase? ( supra 7m gte pistons bmw rods )

[Rusty]

Must be one of those mornings; while watching Larry the Cable Guy travelling around America in search of his next heart attack, I got thinking about the S2 and its future treats (a common daydream for many, I'm sure). Ironic, having just spunked a load of money on it... Anyway, while thinking about the cost of getting the bottom end all sorted out and maybe a nice flowed head on there, I wondered what sort of a stroker motor I could build for the same cost and what sort of turbo upgrades would suit...

Option 1:

• Standard stroke
• Standard bore or slight overbore, perhaps with pistons (depending on bore inspecion)
• Lower CR
• Uprated rods
• Zero balance crank, lightened FW etc.
• All new bearings, rings and seals
• ARP mains and rod bolts (I already have head studs)
• One of JP's lovely flowed heads
• Cost £2500-3000

+ Very strong, will rev cleanly to 7500, no packaging issues
- Revs are limited by lifters and valve springs (could replace), rebore could cause HG issues.

Option 2:

• 95.5 stroke and tall block
• Standard bore
• Custom rods to suit
• Lower Cr
• Standard balance
• Standard mains
• Stock head (checked and rebuilt as necessary)
• Adjustable cam pulley for timing correction
• Approx. cost £2500-?

+ Loads of torque, nice project
- Revs limited to 6500, packaging issues with taller block.

Goal wouldn't be much more than 400bhp but I'd want it to be suitable for track use and thus reliable and not overly stressed. Turbo wise, I'd be looking at a K26/7 hybrid or 3071 on either setup and all the bolt-on stuff would be uprated to suit. Of course, a small inlet 3076R would also be a nice plan, and I could go T3 EM - spec creep anyone ?

Be intersted in what other people think, purely as a talking point TBH, as, let's face it, nothing is going to happen for a while

[Jamo]

Wrong ionformation there, there is no rev issues with the taller deck, the rev issues occur with the 220mm deck and the 92.8 crank

you can rev to stock redline or 7500 with 95.5 crank, some rev over this with dry sump

Cost wise, budget more than that by the way for a stroker

For a track car use the 2.2 with oversized pistons take it to 2.3 litres

Stroker for 400 bhp is overkill for track driving, as the 2.2 setup on track will always be in a higher rev range and negate the need for low grunt IMO unless your going for 600 bhp power

[Rusty]

Thanks for that, usual thing of remembering that you've read something somewhere but perhaps not remembering it right.

The point of the stroker, was that it was a fairly basic build, rather than one that was built to a high spec and it would give a wider torque band for the same turbo, rather than having to rev the nuts off the thing...

[Rocco]

Andy , its waste of money if you spend that kind of money and then you install a "small" turbo... if I were you,I would keep it stock for these turbos. You only would need the hand of Prj(Dmitri)

And if you decide to spend the money,bet for a +480 HP turbo

I don't mind if stroked or not,just my opinion


Classic morning Yes

[Jamo]

Thanks for that, usual thing of remembering that you've read something somewhere but perhaps not remembering it right.

The point of the stroker, was that it was a fairly basic build, rather than one that was built to a high spec and it would give a wider torque band for the same turbo, rather than having to rev the nuts off the thing...

But you have the same gear ratios and at that bhp you aren't getting the benifitswith the extra weight penality

You need to be around 500 bhp really to take advantage of the extra torque and powerband

[Rusty]

What sort of weight penalty are we talking?

[Jamo]

Stroker block is heavier than the 220 In terms of weight I can't quantify, I don't know if AndyP weighed them?

I'll rephrase if you go stroker bugdet for a larger turbo than the 220 build aim for 450-500, I can't think of a turbo that will run 400 bhp on it and not go off it's map, you'd need to run a bigger turbine wheel and housing IMO

[prj]

The stroker will rev to 7500 as well.
I think stroker is a waste of money personally. If you need more displacement go 2.7 biturbo.
3071 is too small for stroker anyway.

You are overthinking this - a bone stock engine with only a K26/K27 or 3071 bolted on, an exhaust and better intercooler will already do 400hp.
You don't need to do rods for that.

If you are looking at a that big engine build, go minimum 3076.

[Rocco]

The stroker will rev to 7500 as well.
I think stroker is a waste of money personally. If you need more displacement go 2.7 biturbo.
3071 is too small for stroker anyway.

You are overthinking this - a bone stock engine with only a K26/K27 or 3071 bolted on, an exhaust and better intercooler will already do 400hp.
You don't need to do rods for that.

If you are looking at a that big engine build, go minimum 3076.

yes +1

but stroker is much more than a little less lagg

and once you are on 2500cc ,with L5 20VT engine i think you will never miss a 2.7bi turbo ... first reason,the sound ,second reason they are quite hard to work on it...too many labour for do maintenaces ,etc on that cars... this is always i heard in Spain

[Rusty]

Enjoying the advice / discussion

[s2_wot]

For 400 brake I think hybrid RS2 turbo + a high end WMI system and tune the car to always have WMI available would give fantastic performance. In theory a least you'd be able to deliver all the boost that the turbo could give low down without knock. That's what I'm working towards at least.

[prj]

Again, if he does not have a RS2 turbo on the shelf, K26/K27 will do 400 all day long with no stress and be cheaper than RS2 turbo plus meth injection.
Of course the meth injection would be awesome for hot summer days, as your car will go very well regardless if it is hot outside.

Maybe I am too price conscious, but I really believe into getting the most bang for your buck.
If that is not an issue, then disregard my advice entirely.

and once you are on 2500cc ,with L5 20VT engine i think you will never miss a 2.7bi turbo ... first reason,the sound ,second reason they are quite hard to work on it...too many labour for do maintenaces ,etc on that cars... this is always i heard in Spain

I think you should drive one, come here for a visit

[Rusty]

I guess that at 167k miles, I'm just thinking that the engine will need a rebuild sooner rather than later, so wanted to make sure that I was planning the right course of action in my head. I see little point in going to the effort of taking the engine out and not doing the job to a standard that will suit sensible future plans (i.e. not a GT35 + turbo ) - I don't fancy pulling the engine out to re-do most of what I'd do the first time... Option 1 was always my intention (in 2 stages, with the head as stage 2), as I was planning on a 3071 (for which I've upgraded the rest of the car) but I think there are some cheaper and very reliable options out there at the mo (2 of which are mentioned above) and the bolt-on nature of a KKK product is very tempting, especially as Dimitri and Richard seem to be getting their teeth into them in a pretty decent way.

When the clutch is suitably uprated, I'll be able to go to something a little more extreme and want to make sure that I can do that as and when I feel like, with bolt-on parts. I've got something to keep me interested for now

A further question - what's the cost of an 83mm overbore? I'll need pistons and a modified or different HG but what, where and £? IIRC, Ross had this (or an 82.5) done to his 3071 3B, with good results. Ta

[prj]

Stock clutch or RS2 clutch can not hold 3071/0.82 anyway.
Richard's is slipping all the time now.

Doing it in stages will just cost more money.
Don't be afraid of the 3076, your car will remain very driveable. Just add meth injection in the future as the 2nd stage and get 550hp.

If you are doing 83mm, get 7M-GTE pistons, BMW rods.
They can hold a 3076, and will be almost free

[Rusty]

7 years of 240-300bhp hasn't exactly been boring, so 550 must be mad.