8000 rpm/300 bhp 3.2 rebuild

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911hillclimber
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8000 rpm/300 bhp 3.2 rebuild

Post by 911hillclimber »

Thought it best to start a thread on the rebuild of my engine out of my hill climb Lola sports racer:

Image

The car currently has a stock 3.2 engine with DIY headers, PMO carbs and a flat fan conversion made by Crispin Manners for the engine's previous owner.
I wont bore you all with the story (a long one) behind the car, but I've been hillclimbing it for over 10 years and have won lots of Class wins in the Midland Hillclimb Championship.

The gearbox is a mag cased 915 some special bits inside inc a LSD, bit more on this later.

The car is not fast enough for various reasons, so time to take this very heathy engine and modify it to take 8K rpm and maybe generate 300 bhp and 270 lbft.
This is the purpose of this project.

It will be the last evolution of this little car before we retire together.

This thread will detail the various things that can and will happen as I DIY this engine which ha to be fully tuned and running by the end of March 2022, the start of the season at Prescott hillclimb.
It will be a slow start then will get very busy.

Spec:
JE Pistons @ 10.5:1, Ordered, arriving Xmas 2021
Carrillo rods to 8500 rpm, Ordered, arriving Xmas 2021
GE 60 cams from Kent Cams
Light spring kit
Twin plugged heads if I can find someone to machine them!
Twin plug ignition from Clewitt
Keep the carbs
Replace all the bearings etc and build up from the crank.
Probably a few other things as we go along.

The 915 will get a WEVO Shift Gate mod done by the builder of the box, Mike Bainbridge, safe hands.

So, we have to get it apart which I have spent a few hours on. First time this drive train has been out of the car since the last huge engine blow-up...5 years or so ago.
Engine oil out, nothing on the magnetic pug ( :) ), box oil out after 10 years and clean, small steel filings on mag plug, nothing scary.

Exhaust and gear change linkages off, transmission cross member and support frame.

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With that lot clear, the drive shafts freed off, engine frame braces off, fuel line off and it's regulator, engine loom free, alternator off and finally the carbs.

Image

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With the inlets fully open and with some trepidation, I shone a torch down each cylinder. What a lovely sight! All perfectly clean and looking new, love it!

Image

The WEVO kit is on order, ex stock at Twin Spark and I will call Mike when I have it to get the box to him. Be nice if he is coming to the Swap Meet to save me a run to the Lakes.

The 911 will go into professional storage in Nov so to free the 1/2 garage space to do the engine.

I just wish I could find someone to machine the heads for twin plugs!
People say they do them, but never respond when asked. :|
73T 911 Coupe, road/hillclimber 3.2L
Lola t 492 / 3.2 hillclimb racer
Boxster 987 Gen II 2.9
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KS
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Re: 8000 rpm/300 bhp 3.2 reuild

Post by KS »

Twin-plug: Rodwell Motorsport. 07712 002578. It's who Bob Watson used when he moved down to Dorset.

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Last edited by KS on Thu Oct 07, 2021 5:28 pm, edited 1 time in total.
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Gary71
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Re: 8000 rpm/300 bhp 3.2 reuild

Post by Gary71 »

Going to be a great build :)
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Re: 8000 rpm/300 bhp 3.2 reuild

Post by greg356a »

Looking forward to this post. Lots of pics of each stage please.
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911hillclimber
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Re: 8000 rpm/300 bhp 3.2 reuild

Post by 911hillclimber »

Thanks Keith.
Maybe people will only quote if they are doing the engine build? I'll contact them tomorrow.

Gary: I do hope so, it is going to cost a lot, so needs to deliver!
73T 911 Coupe, road/hillclimber 3.2L
Lola t 492 / 3.2 hillclimb racer
Boxster 987 Gen II 2.9
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hot66
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Re: 8000 rpm/300 bhp 3.2 reuild

Post by hot66 »

Have you checked wether the heads with those valve sizes and ports can flow enough air for 8000rpm ?
James

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911hillclimber
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Re: 8000 rpm/300 bhp 3.2 reuild

Post by 911hillclimber »

No! I have not James, mainly because in all my preparation todo this project, nobody has said they do or don't.
This engine I want to take 8k but it may not need to, much depends I think on the cams, and Several have assured me the GE 60 spec is correct for my purpose.
It must be a flexible engine, no cam surge before things happen, so I expect 7600 or 7800 may be the max point of the curves.
73T 911 Coupe, road/hillclimber 3.2L
Lola t 492 / 3.2 hillclimb racer
Boxster 987 Gen II 2.9
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Re: 8000 rpm/300 bhp 3.2 reuild

Post by sladey »

Looks interesting. 300 seems ambitious without increasing capacity but I'll be very happy to be proved wrong
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neilbardsley
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Re: 8000 rpm/300 bhp 3.2 reuild

Post by neilbardsley »

I think the engine makes 250 now?

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Re: 8000 rpm/300 bhp 3.2 reuild

Post by RobFrost »

911hillclimber wrote: The car currently has a stock 3.2 engine with DIY headers, PMO carbs and a flat fan conversion made by Crispin Manners for the engine's previous owner.
You say stock 3.2, you mean originally a 1980s Carrera 3.2 Motronic unit, right?

For fuel delivery and ignition, have you considered the Triumph ITB option Impmad has in his 2.2? - I suspect you might get better power and cost-effectively too, than carbs.
1970 911T, Signal orange (Restoration thread)
1988 3.2 Carrera backdate, Black
2001 996 Turbo, Lapis blue (am I allowed to put that here?)
I'm looking for a pre-impact bumper 911S or other high-revving 911 to restore - please let me know if you see one.
911hillclimber
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Re: 8000 rpm/300 bhp 3.2 reuild

Post by 911hillclimber »

Current engine gives 261 bhp off the rollers 4 months ago, so no imaginary numbers, and iirc 240 lbft. @ 6300rpm. Bob Watson got 264 bhp.

300 is my target, 301 is good enough. It is the ability to run to 8K rpm that matters most to me.

The base engine is a simple 3.2 from 1986, carbs and coil ignition.
I plan to run the carbs again (injection throttle bodies too expensive and gives me very little more), but expect to use Clewitt twin spark ignition like James'.
I had the complete Triumph units once, but doubted they could deliver for a 3.2, Impmad's is a 2.7, so sold the lot years ago.

I'm ok with the direction I'm embarking on.

Remember this is a hill climb engine, mostly ticking over or wide open throttle for less than a minute hill climb time, nothing subtle going on here.
It does about 6 mpg.

Pleased though that you all are putting it under scrutiny, will need positive comments in about 8 weeks time when the going gets 'interesting'.

I also want to keep the vintage classic old race car look after all is done simply because I love it.

Image
73T 911 Coupe, road/hillclimber 3.2L
Lola t 492 / 3.2 hillclimb racer
Boxster 987 Gen II 2.9
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Re: 8000 rpm/300 bhp 3.2 reuild

Post by impmad2000 »

Impmad’s is a 2.2, but the rule of thumb I’ve always used is look at what the bike makes (120bhp at 9200) and the car should be capable of making about the same…. Obviously 2x 120bhp as there’s two. A bike TB will shift a lot of air and fuel as they’ll Rev higher, not that the Triumph is a particularly high reviver). So roughly Graham, if you are after 300bhp you would probably have struggled.
Crank fire ignition should be much better though .
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sladey
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Re: 8000 rpm/300 bhp 3.2 reuild

Post by sladey »

I was saying optimistic because mine is 265ish - that's with Canems ECU and MAP sensor, 993 Heat exchangers, rebuilt by Mike Bainbridge. I've still got stock Cams in it and it's single plugged. On all the 3.2 stuff I've followed on Impact Bumpers people generally top out at 270 unless they go for a capacity increase. I know Richard Bernau did a hell of a lot with (IIRC) a 964 induction system and that's also 262 on Wayne Schofields dyno

Good luck to you and I hope you get it - be interested to watch your journey
The simple things you see are all complicated
I look pretty young but I'm just backdated yeah
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Re: 8000 rpm/300 bhp 3.2 reuild

Post by RobFrost »

911hillclimber wrote: 300 is my target, 301 is good enough. It is the ability to run to 8K rpm that matters most to me.
I was researching what hp is possible and this gives an idea:
https://www.goodwood.com/grr/road/news/ ... per-litre/

If we assume without the variable valve timing of a modern car you couldn't get onto that list, the Honda attains 125PS per litre at 9,000 revs. If we assume your 8,000 rpm gets you 8/9 of that, your theoretical ceiling in a 3.2 litre is 356PS or 347hp.
1970 911T, Signal orange (Restoration thread)
1988 3.2 Carrera backdate, Black
2001 996 Turbo, Lapis blue (am I allowed to put that here?)
I'm looking for a pre-impact bumper 911S or other high-revving 911 to restore - please let me know if you see one.
RobFrost
Put a fork in me, I'm done!
Posts: 1917
Joined: Thu Jul 08, 2021 8:18 am
Location: Lichfield

Re: 8000 rpm/300 bhp 3.2 reuild

Post by RobFrost »

How do you go about reversing the drive? I had been wondering if that were possible, to make a mid-engined car. Simplest solution I could imagine was an upside down diff - is it as simple as that?
1970 911T, Signal orange (Restoration thread)
1988 3.2 Carrera backdate, Black
2001 996 Turbo, Lapis blue (am I allowed to put that here?)
I'm looking for a pre-impact bumper 911S or other high-revving 911 to restore - please let me know if you see one.
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