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-   -   2.5 Conversion (https://www.scoobynet.com/drivetrain-11/363317-2-5-conversion.html)

GRIFF007 23 September 2004 10:20 PM


Originally Posted by john banks
Griff, I have these from my five speed run 40-90mph in 3rd on AP22 on my old five speed box with similar power and torque to present, with a passenger, in the wet, damn I really used to like that 3rd gear :D :

mph time(s)
40.0 0.00
50.0 0.93
60.0 1.77
70.0 2.64
80.0 3.62
90.0 4.83

60 - 80 in 2 secs - err thats nippy - what torque is that?

john banks 23 September 2004 10:48 PM

400 lbft. With more boost and just me in the car I did have a 1.6 or 1.7 60-80mph but that is overdoing it a bit on standard Cadbury internals ;)

GRIFF007 23 September 2004 11:14 PM


Originally Posted by john banks
400 lbft. With more boost and just me in the car I did have a 1.6 or 1.7 60-80mph but that is overdoing it a bit on standard Cadbury internals ;)

how about http://axispowerracing.net/stage2motor.html for £1600 short motor that might hold together ok?

Houghton 24 September 2004 01:04 AM

MY97 STi3 in a similar situation to U Wot (without the bang), just crankcase compression. Having sat down with David & costed a re-build, decided to go for 2.5 (reg doc already says it's 2.5) I must say I find this thread all rather worrying.

Can't expect a warranty as the block isn't their supply but It's booked into API in a couple of weeks for the transplant, spec as follows:
Apexi Power-FC (Andy F to re-map)
AVC-R Boost controller
Hybrid FMIC
TD05/06 20G
550 Injectors
Walbro pump
FSE reg
Gruppe-S headers
H&S d/p
Samco Inlet
Lightened billet f/wheel AP clutch

It's a daily driver 20K+ pa & occassional track day, I realise the g/box will be the next thing to address but from the sound of this thread the engine won't last that long anyway. On the other hand there's plenty of stories of 2.0 rebuilds going pop soon after and more than once.

Not looking for the 500 bhp talked about here but hoping for a reasonable hyke from the current 320ish
Gerry

911 24 September 2004 06:43 AM

I'll watch your progress with great interest Gerry. Please make sure you let us know!

I'm chasing the same spec on my Stiv3 but on the stock engine.

I think some of the 'blow-up' here on 2.5's are honest drives to the maximum; where are the limits.
I'm sure if you tune the car to match the weak link (trans) and after the inevitable 6 speeder is in you can get it hiked-up accordingly!

API are 1st class.

Good luck. 911 :norty:

U WOT! 24 September 2004 06:48 AM

How much is that costing you Gerry, if you don't mind saying.

Houghton 24 September 2004 08:51 AM

Hi 911,
Apart from the Samco & 20G, the rest are already on the car with standard VF23. It runs well but smokes from VTA breathers (not exhaust) and oil dripping on headers. The appeal of 2.5 is more flexibility from earlier torque & boost. The worry is minimal piston/bore clearance that's been spoken of, often.

I don't have any concerns over API, heard nothing but good reports and having visited their premises and discussed the options, am confident of a first class job.

U Wot!
As David mentioned he doesn't want his prices published, I'll PM what was discussed, presumably you've had some costings when you spoke with David?

Gerry

john banks 24 September 2004 11:45 AM

Griff, I think the big ends would be next, so I just put another EJ257 in. 440 BHP and 400 lbft as I am running now approx with no additives on a very safe map feels nice, isn't too hard on tyres and other consumables, plus I can get away with a nice feeling organic clutch.

911 24 September 2004 12:46 PM

John, you make it sound so easy....

The formula to get a 2 litre to 350/320 is well known, understood and affordable (ish).
That is: TD05 hybrid/Apexi fc/andyf map/headers/550+Walbro/full 3'' decat/TMIC

Take the same engine, ie Sti v3 with above, and start with a 2.5 USA short block (of what spec?) and build it up.
Just what do you do/use to get the rosey sounding 400 bhp/380 lbf (ish) result?

Finally, is your gearbox fitted with different internals or is it a 6 speed?

911 :norty:

john banks 24 September 2004 01:48 PM

Easy when you've done it all the wrong way, and when you have Andy F to supply ideas that you can copy ;) Most of my development over the last year or two has been fuelled by his ideas, refining them (compromising them really) for what I think is a nice daily driver.

Yes my six speed is standard internals, it seems up to the job so far.

Recipe for 400/380, I would use a standard EJ257 block, need to select the right gaskets to go with your STi 3 heads, to get the CR in the low to mid 8s:1. Other than that very similar to the 2.0. You should only need about 1.3 bar to get 380 lbft.

David_Wallis 24 September 2004 04:09 PM

Personally I would go for a higer rather than lower CR.

(I run low compression on my own engine)

David

john banks 24 September 2004 05:09 PM

I'd agree with you there David, I think the engine would last longer at higher power as well as being less fussy about octane and possibly making more power for the same octane. I thought I noticed a slightly improvement low down going from 8 to 8.7:1 approx, but I'm a sucker for the placebo effect like everyone.

911 24 September 2004 06:18 PM

Interesting. From that data the stock 5 speed is going to be overwhelmed by that torque, especially with the car on hill climb slicks so little wheelspin. Was your box a Jap Sti or UK box?
Thanks for the info both, helps a lot.(you get an idea of the bloody cost....)

Just a thought, is a FMIC essential, or will the 2.5 run 'ok' @380 bhp/1.3bar on a V8 TMIC?

That sentence looks like a text message!

911 :norty:

john banks 24 September 2004 06:28 PM

UK 6 spd m8. TM vs FM dpnds hw lng on gas 4. I wud try TM 1st.

;)

Mark A 25 September 2004 01:38 PM

bump

buzzard 25 September 2004 02:49 PM

injectors
 
fantastic thread it has to be said.i'm just about to start a rebuild using the 2.5 and while i love power ive decided to settle for a nice daily 320/320 as reliability is really what i'm after now. i intend using all the original parts from my 96 wrx(tdo5) and have it remapped to suit. i wondered if there is any great need to up from the 370 to 440cc injectors or not?
comments appreciated.
thanks a lot.

911 25 September 2004 05:35 PM

If your car was focused on hillclimbing John would you use a JDM Sti trans instead of the UK 6 speeder bearing in mind the lack of max rpm inherent in the 2.5 stock short block?
As you say Buzzard, this and similar threads make Scooby ownership and modding that much more interesting.
You have to hand it to JB/DW/AndyF and that 'clan' to achieve what they have, sure glad they don't hill climb :D:

911 ( leading my class today at Prescott :p :norty:)

john banks 25 September 2004 05:45 PM

I don't know much about hill climbing 911 except that you go through a timed course one at a time and they can be quite twisty.

That being the case I would have thought that a bigger engine with a wide power band would be king - less of a difference between off boost and on boost performance, better response in lower gears, in other words more normally aspirated. Do you get over 100 mph, if so, the UK box does have a jump from 4th to 5th, both JDM and UK boxes would need you to be busy (too busy?) with the box for a twisty course/circuit, quite like an RA, or worse if you have a lot of torque as well.

911 25 September 2004 06:04 PM

!
Hill climb similar to your description but bends are tight and the trees just a meter or two away...
The starts are real drag racing starts, 4500 and dump the clutch hard.

I tried an RA box on 4.11 diffs early this year, and the time to keep-on changing gear just when braking and steering was too much in the dash of everything. Went quicker with my Sti trans back in place!

The 2.0 or the 2.5 with big torque has me worried with Avon slicks on.

I think the 2.5 plus the 2.L mods from the above would work really well on the hills, bags of flexibility.
Before MarkA temps me again with the 2.5 block, will do the 2.0L this Xmas, and the 2.5 next one! (and a 6 speeder mid season next year I think...bang!)

Where does this all stop?

There is an EVO 5 with 460 bhp next to me this weekend....but I'm faster in the wet :p

911 :norty:

Tim W 26 September 2004 01:41 PM

If I can find the time (and the spare cash) I hope to start doing some Hillclimbs and Sprints with my car once it's togehter again...should be interesting, it's in the process of having a 2.5 build installed along with a 6 speed ;)

911 26 September 2004 06:38 PM

That's a good start, but you will need a very good chassis also!
Good luck, and save a LOT of £££££££££££££££££££££££££££££££££££££££

Expensive hobby, but GREAT fun.

911 :norty:

Tim W 26 September 2004 07:00 PM

I don't think this thread is the place to list the spec of my car, but let's just say I've been playing around with the chassis for longer than I have the engine ;) and I started playing with the car after my first trackday with it in 1998 when it was 3000 miles old...

I only started the 2.5 build because we (Mark Aigin, Pat and I) decided that we'd pushed my poor old slappy engine too close to the edge and it was going to die, so it was time to try something new :D

911 26 September 2004 07:48 PM

That MarkA is a bad influence!

Looks like this could develop into a nice hill climber!

911

David_Wallis 26 September 2004 09:14 PM

Ive got to hand it to tim, he was very quick around donnington a couple of years back :)

When I say higher CR - im talking about 911's engine.

Higher CR would be better IMHO..

I would concentrate on something that Pulls Extremley well from nothing.

What rev range are you normally in? how slow in 2nd? ie what revs?

Racefuel / Methanol allowed?

I would run something stupid like toluene methanol and petrol and maybe ATF in with it.. depending on mixes..

Charge temp may also be lower depending on fuel..

Certainly wouldnt bother with a fmic, just a top mount with water spray and maybe C02 spraybars..

I would also look into running water inj with methanol.. and get a serious map done.

Also things such as ALS :)

I think concentrating on things like the rally cars use would be sensible..

depends what your regs are??

David

Tim W 26 September 2004 09:26 PM

Actually it's the regs that bother me, or rather the classes, I've got this nasty feeling that I'd be lumped with the big boys who really know how to drive and have very well developed cars, purely because of the number of mods that have been done to my car...I think the only untampered with part of my car is the bodyshell excluding the bonnet and boot lid :rolleyes:

(PS thanks David ;) )

Pavlo 26 September 2004 09:30 PM

Looks like Mr wallis has seen the light!

Roll on smaller turbo, lol! or maybe just the nitrous!

Paul

911 26 September 2004 10:14 PM

David, if you are looking at today's hill climb regs, try this:

Class C1 = 2000cc and anything over, saloons only.
Engine MUST be the original block, ALL mods are free (ie 2.2 stroker ok)
Induction/exhaust Free
MUST be petrol, NO addatives except octane booster (not too sure about that either)
ALL suspension points must be as stock, otherwise free.
Any ecu/tricks etc allowed, though ALS getting a bad press due to noise (especially GEMS system)
Tyres are free choice as are brakes

There, dead simple. So, a 2.5 as above threads are ok, a 911 engined car is not.

Today my car raced hard against a 460 bhp EVO5 (deffo not standard...) and spent many a dash to the rev limiter and back, 8400.
Drove home nice and easy.

You need a good chassis/tyres then a stonking engine full of torque. For that you need about 6K in a Scooby. You only get 2 runs to clock your best time, do or die!

Bit like drag racing with bends and trees.

:norty: 911

R19KET 27 September 2004 12:02 AM

911,

Sorry, can you clarify something please.


Engine MUST be the original block, ALL mods are free (ie 2.2 stroker ok)

So, a 2.5 as above threads are ok
If the first statement is true, how can a 2.5lt be legal, unless it's the "original block" with an over bore/re-sleeve/stroked ?

Please can you post the web site which shows all the rules.

Mark.

Tim W 27 September 2004 01:56 AM

Mark, you'll probably find all the information here at the Hillclimb and Sprint Association website: http://www.hillclimbandsprint.co.uk

It's not that I've been reading Colin Goodwin's articles 'How to get started in motorsport' each month in EVO or anything ;) Which reminds me, I still owe Mr. Goodwin a call about the first ever Autocar trackday, I want the pics of my 'moment' on Craner curves...and Trout probably still wants the address of Andrew Fr(w)ankle so he can go give hima slap ;)

Tim W 27 September 2004 02:09 AM

Ah, on reviewing the regs it looks like you also need to refer to the MSA and get a copy of the Blue Book...this site was quite useful


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