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Jonny Hart

3.5L MFI twin plug. 380HP and 330 ft lbs

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Agreed, i'm aiming for 993SS cams and decent breathing/management then focusing on Lotus style "light is fast" ethos :ani_nerd:

I think even if someone gave me a 380bhp engine, my 915 would take one sniff and decide to permanently leave the country :blink:

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8 minutes ago, MarkJ said:

you don't need that much in one of these cars anyway. Put a 3.6 in it and it will be all the power and fun you will need in an IB on track or road. I envy Jev and co who did their 3.6 transfers before all the engines (and anything Porsche!)  started fetching stupid prices. So wish I had the money back then to do it.

I reserve the right to change that opinion if somebody wants to put a 380bhp engine in my car :D

I’ve driven cars with 3.6’s. These bad boys are a different animal. Vicious was how I remember that 400hp car. Maybe with a bit of savage. You probably wouldn’t want it all the time though. The guys who had it trailered it to Anglesey in an enclosed trailer pulled by a landy.

I’d have one in a heartbeat but it’d have to be a special occasion or track car. Certainly not something to go for a road blast in on a sunny Sunday afternoon.

To be honest, if you want that kind of super special performance, you’re better off buying an atom at a fraction of the cost. 

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I think you can still do the 3.6 conversion yourself for not ridiculous money if your a hands on type doing everything yourself , many on here have rebuilt their own engines .  Particularly in a time when some specialist builders are charging bonkers money for a warmed engine. :twocents:  . 

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Meanwhile on Facebook, jenvey itb’s and coil on plugs..... Wonder how many hp that’ll make. 

4223C2B2-39EE-4AAF-BBCE-8C668B367DA7.jpeg

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Great thread!  Love it.

Remember, its easy (relatively) to build a race engine and makes lots of hp - Porsche were making 330hp from 3.0 litres back in the early 70s with MFI, RSR cams, big valves and very loud exhausts.  When I was not long out of University, my mechanic was racing a 3.5 litre IROC rep making a super reliable 350 hp with S cams, EFI thru MFI stacks and first generation Motec.  It was not a highly strung engine at all.  The secret ingredient in all the air cooled race builds is revs (and £££).  Just the same as a GT3 motor - only modern tech gives you more drivability, longevity, reliability economy and less emissions and noise - because science (and witchcraft - obviously).  In crude terms, all a GT3 motor does vs a cooking water cooled motor is rev higher and keep breathing at those high revs.

Follow the proven recipes and hp follows.  What is more difficult (as we have seen on some of our favourite rebuild threads) is when you try to do something different, particularly when you want a nice friendly street motor.

If you start with a 3.2 and patch stuff onto it (even lots of good stuff), you still end up bumping up against limitations.  If you start with a clean sheet and build everything to run efficiently at 8000rpm, then you will make tons of hp.  And some compromises. 

Still, lovely to see cool pics of high power, old school, air cooled stuff.

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Loving this thread too having popped in to see Steve at Jaz today and having seen the engine build guy(s) at work. He is currently doing some work on my car  for me (Brummies blue 3.6 in a 1979 SC) and funnily enough it is currently nestling under your red beast Richard B which is up on a ramp. I have been immensely impressed with the whole Jaz Porsche operation so far and Steve in particular. His knowledge and attention to detail is amazing and he is genuinely interested in saving the customer money where possible. I cant see anyone else touching the car but him going forwards.

Steve was explaining the exhaust system to me on the 3.5. Sadly most of it went over my non engineering head but he explained that it is controllable like a 997 with the ability to press a switch and either have it running as a snarling animal or muted and quiet.

Beaky's engine (I think) was nestling in a corner and that looked lovely

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A few of us had coffee and bacon sarnies there with Steve a while back - a chat about CIS and air cooled stuff in general. There can't be many workshops with more experience, equipment and knowledge.

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7 hours ago, Busybee said:

Meanwhile on Facebook, jenvey itb’s and coil on plugs..... Wonder how many hp that’ll make. 

4223C2B2-39EE-4AAF-BBCE-8C668B367DA7.jpeg

oooofff! do the lower coils have heat shields or fresh air blown over them ????

can anyone read the part numbers/manufacturer on the COP's

Edited by World Citizen

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1 minute ago, World Citizen said:

oooofff! do the lower coils have heat shields or fresh air blown over them ????

Can you tell it’s twin plugged from that WC? No idea Mate. Hot hot hot. 

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7 hours ago, Richard Bernau said:

my mechanic was racing a 3.5 litre IROC rep making a super reliable 350 hp with S cams, EFI thru MFI stacks and first generation Motec.  It was not a highly strung engine at all.  

Do you remember at what rpm did it get the 350 hp?

7 hours ago, Richard Bernau said:

The secret ingredient in all the air cooled race builds is revs (and £££).  Just the same as a GT3 motor - only modern tech gives you more drivability, longevity, reliability economy and less emissions and noise - because science (and witchcraft - obviously).  In crude terms, all a GT3 motor does vs a cooking water cooled motor is rev higher and keep breathing at those high revs.

Nice way to put it!

Roughly what do you reckon is the max rpm one should run on an SC engine without modifying the internals? 7000 rpm? I'm thinking about 100-200 hours of hard driving between engine rebuilds.

8000 rpm sounds like a lot for those old engines. What modifications would be necessary to get there?

 

 

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7 hours ago, Richard Bernau said:

Great thread!  Love it.

Remember, its easy (relatively) to build a race engine and makes lots of hp - Porsche were making 330hp from 3.0 litres back in the early 70s with MFI, RSR cams, big valves and very loud exhausts.  When I was not long out of University, my mechanic was racing a 3.5 litre IROC rep making a super reliable 350 hp with S cams, EFI thru MFI stacks and first generation Motec.  It was not a highly strung engine at all.  The secret ingredient in all the air cooled race builds is revs (and £££).  Just the same as a GT3 motor - only modern tech gives you more drivability, longevity, reliability economy and less emissions and noise - because science (and witchcraft - obviously).  In crude terms, all a GT3 motor does vs a cooking water cooled motor is rev higher and keep breathing at those high revs.

Follow the proven recipes and hp follows.  What is more difficult (as we have seen on some of our favourite rebuild threads) is when you try to do something different, particularly when you want a nice friendly street motor.

If you start with a 3.2 and patch stuff onto it (even lots of good stuff), you still end up bumping up against limitations.  If you start with a clean sheet and build everything to run efficiently at 8000rpm, then you will make tons of hp.  And some compromises. 

Still, lovely to see cool pics of high power, old school, air cooled stuff.

What’s the basic recipe of mods to get 300hp from a 3.0 litre engine RB? Not that I ever will I guess but be interesting. 

4 minutes ago, World Citizen said:

just a guess considering the amount of HP

I was speaking to the guy about his engine. He’s doing all the work himself including grinding cams (can you grind cams yourself?). Says no idea what hp but thinks 260/270. Coil on plug is quite rare for these engines isn’t it? 

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22 hours ago, Jonny Hart said:

A few people not paying attention.  It’s a Steve Winter (JAZ) built engine,  setup by BSM on their dyno. 

Aha, missed that. Well there's your answer then - Get Jaz to build your motor and stick it on the BSM dyno to run it in. Then the thing should stay in one piece and you will get it within 2 years. 

9 hours ago, Sidewaysfun said:

I think even if someone gave me a 380bhp engine, my 915 would take one sniff and decide to permanently leave the country :blink:

Yes, but it is the torque as much as the bhp that kills the 915, especially already stretched ones, they really struggle. I've been fighting this for the past few years. 

8 hours ago, Busybee said:

I’ve driven cars with 3.6’s. These bad boys are a different animal. Vicious was how I remember that 400hp car. Maybe with a bit of savage. You probably wouldn’t want it all the time though. The guys who had it trailered it to Anglesey in an enclosed trailer pulled by a landy.

I’d have one in a heartbeat but it’d have to be a special occasion or track car. Certainly not something to go for a road blast in on a sunny Sunday afternoon.

To be honest, if you want that kind of super special performance, you’re better off buying an atom at a fraction of the cost. 

Stick even a standard internals 3.6 in an IB and you end up with an engine that has completely usable power all the time as well as the same reliability as a stock 964/993. You also get better hp, mpg (than the donor car), torque and because it's a lighter car it pulls from really low revs and the whole thing comes alive. These things only become unusable when you start adding big cams and doing more extreme mods. Tripes old 3.6 was the perfect example of a great 3.6 sleeper.

44 minutes ago, World Citizen said:

oooofff! do the lower coils have heat shields or fresh air blown over them ????

can anyone read the part numbers/manufacturer on the COP's

A friend of mine is blazing a trail with COP using VAG parts. Happy to pass on the details if you want to follow his progress.

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18 minutes ago, ALEX P said:

A friend of mine is blazing a trail with COP using VAG parts. Happy to pass on the details if you want to follow his progress.

yes please Alex, I might be able to help him if the lower COP's start getting too hot and become unreliable

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8 hours ago, skullcandy said:

Beaky's engine (I think) was nestling in a corner and that looked lovely

Correct, just await a piston ring and it’ll put together 

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Just for kicks we did a pull with only one CDI box, (as if it was a single plug).  Lost 40 HP. 

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20 hours ago, Busybee said:

Meanwhile on Facebook, jenvey itb’s and coil on plugs..... Wonder how many hp that’ll make. 

4223C2B2-39EE-4AAF-BBCE-8C668B367DA7.jpeg

Are individual coil packs the best solution for these engines?

Always thought that they combustion arrangement is better suited to a big spark.

 

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15 hours ago, World Citizen said:

yes please Alex, I might be able to help him if the lower COP's start getting too hot and become unreliable

Not wanting to stray too far off topic but most of it is on Facebook:

 
The car is a super tidy 964, there is most of the build here. He's going from coil packs to COP but don't think he's gone into a lot of detail about the Audi COP yet.
 

thumbnail_FB_IMG_1544191898799.jpg

thumbnail_FB_IMG_1544191887959.jpg

thumbnail_FB_IMG_1544191893426.jpg

Edited by ALEX P

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A couple of Qs above about the "recipe".

On the kiwi "IROC RS", it wasn't revving massively high as it was only on S cams, which are mild for 3.5 litre build.  They were peaky on a 2.4 and lovely on a 2.7RS.  Jon Waring was the owner, builder and being a mechanical engineer by trade, he was meticulous.  The engine had all the right parts, but nothing secret or that you can't do now - best guess it was something like this:  lightened and balanced crank, LW Carillo rods, Mahle forged pistons, Ti valve retainers, twin plug, motec.  The car used MFI throttle bodies converted to EFI and bored as wide as you could given the need for some wall thickness. Probably smaller than 46mm Jenveys for perspective.  Exhaust was fairly standard 3-into-1, equal length stuff going straight back and out through a small silencer on either side, meaning no rear muffler and a separate system per side. That's about all I can remember.  The rev limit would have been in the 7400-7500rpm area and peak power would be higher than a 993SS cammed motor, but still in the 6s.  Actually, I also recall it made the most hp with the original 2.7RS style airbox with no filter compared to all other filters or no filters options.  Some early resonance tuning going on maybe.  Also good to note that the car was exhaustively tuned on the dyno - easy with motec - so it was optimised.

No doubt you can google the specs on a 3.0RSR motor, but its not so far from above IIRC.  I think they had Ti rods, everything lightened, massive valves and the RSR or sprint cams with massive lift, duration and overlap.  With MFI dumping bucketloads of fuel in, they only really work at high rpm.  Leonard Stolk's green car (the Hulk) that some on here know and have seen at Spa and which I followed for a week in the Alps a few years back, makes over 300hp from 3 litres and when he uses it on the road on say a hairpin, he uses 1st gear and describes it as "chug, chug, chug, waaaahh!!!!" meaning it kind of does nothing until it hits maybe 4500rpm then it screams.  He was on 2 fuel stops per day versus one in the 3.2 - say 12mpg vs 24mpg.  Leonard's favourite car for the Alps is Woodstock - a yellow 2.8RS motor in an ST type body.  He did speculate that the RSR engine in Woodstock might be kind of fun though.

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On 12/6/2018 at 4:55 PM, Sidewaysfun said:

I think even if someone gave me a 380bhp engine, my 915 would take one sniff and decide to go on an expensive holiday in lake district :blink:

Fixed it for you 

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I seem to remember Brian of RarlyL8 fame writing similarly on the durability of the 915 for given power increases. 

I think it was in the context of turbo'd motors, with associated gearing issues etc. 

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Its the torque that's the killer. There are a few options to upgrade/fix or even go silly with ruf CTR 5 speed turbo box which can handle a lot more than needed here.

Does anyone know much about wevo race case systems?

https://www.wevo.com/Products/TransmissionProducts/WevoTransmissionProducts-RaceCaseSystems.htm

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