Anonymous

...right as i am going Grp A type replica i think i want to go rally style engine...my new unit is 7.9-1 comp ratio with big ported head and big cams...what power did a grp a run?????I am happy to run 4 greys and anti lag on the T34 .63 with my engine mods how do i get say 500ft lb and 300bhp?...I take it restrictor...if you derestrict i assume the torque comes down...i want blistering 0-60 times like the real rally car not interested in top end....

Mike Rainbird

iTrader: (3)

500lb ft would kill the gearbox with one press of the pedal .

Drop the final drive to 3.9 and get engine converted to "Billabong" spec (will STILL need a big tooth gearkit) .

Anonymous

Mike...nope i want a full rally type spec well as close as the grp a cars....does the restrictor get you the torque?

Come on pf give me your knowledge

I want 0-60 in 3 secs in the wet and whatever a rally car goes top end!

Transmission aint an issue will all be sorted.

Stavros

Why will a restrictor gain you anything at all?

Im not 100% it wont, but cant see how it can at all.
Seems like a myth to me.

Rally engines are so torquey due to engine spec, not the restrictor.
Unless a rectrictor cures compressor surge which is what enables the cars to run 3.5bar+ or whatever mad boost spike they run, which is of course what gives you torque.

Id love to REALLY know, all i hear is rumours.

Stu @ M Developments

iTrader: (12)

Skim a lump off the head to get the compression back to something sensible, run 40psi peak and keep the restrictor to stop even you making an arse of your power goal, that will put you in the ballpark.

foreigneRS

how do you imagine that a restrictor gives you more torque?

absolutely clueless

GARETH T

you gotta look at how power and torque is connected

Mike Rainbird

iTrader: (3)

Phil,
I have been driven in a rally car with restrictor on the road and they are PANTs. Do NOT go down this route, you WILL be dissappointed. Power tails off so much at top end that it feels like a parachute has been deployed . You certainly will not want 4.4 diffs .

I'm serious about Bill's engine - TRY it, it WILL blow your mind .

Anonymous

To allow rediculous boost peaks without surge thus getting the torque?

...clueless is better than being German in my book!

Disabled Account

Mike, were some of the rally engines also very low compression....like 6.8:1 ? I noticed in the Cosworth catalogue that they do 6.8: 1 comp pistons....

allsteel

Rally motors were running high compressions,around the 9 mark and had small ports in the head.Big ports for power,small ports for torque.Oh and a nice drop of 102 octane fuel.

Mike Rainbird

iTrader: (3)

Doug,
That was the TOURING cars, the rally cars run massive high compression to compensate for the lack of boost at the top end that the restrictor dictates. The Grp A cars were running 9.5:1, which increased to over 10:1 for the "world" engines.

foreigneRS

so now you can read other peoples replies and repeat them parrot fashion you're an engine guru?

Porkie

iTrader: (1)

One of the best mods I ever did to my car. Transformed it

and you should have bought my freshly rebuilt bigtooth box. That was a Steal at Ł2500!

Anonymous

...will a T34 DO 40psi?.....

Mike i think i would retain std gearing as i know what you mean about 4.44!!!

Billys engine is just like my old T38 specced one but maybe a little quicker...so bgeen there done that and will agree VERY fast...BUT if i restrict it as Stu says on a .63 then massive torque but say 18psi at top end for the 300ish bhp....then i cant blow it up thru no fuel top end NOT that i have ever done that

Porkie

iTrader: (1)

Why not drop the Final drive Phil? Its a great great mod

Anonymous

German bloke you laughed at a restricter making more torque We should be laughing at YOU If it allows higher boost to be sort then surely it makes more power?

Ok so i need smaller ports...got that here SO i could do this to my EEC4 engine thats done 37k miles...8-1 ish P8...then put the GT35 on the other engine when this pisses me off

Mike Rainbird

iTrader: (3)

Phil,
For short periods, but I'm sure like the rally teams you'll replace it regularly anyway .

If you want the PUNCH and aren't interest in top speed, go to the 3.9 diffs .

If you think that would make a nice road engine, you're living in a dream world. Listen to what I said about having been in the car thus equipped (I'm talking about an Ex-Ford works car as well - one that cost Ł250k to build ). My sapphire which only had 385bhp would have MURDERED it on anything other than a rally stage or really tight twisty track. I was so dissappointed with the performance it was unreal (obviously the handling was on a different planet, but on track, it's power and gearing would have hampered it beyond belief).

Anonymous

...when you say difference Porkie in what way...just quicker accelration?

Mike Rainbird

iTrader: (3)

Phil,
Sharpens up the response and because it shortens the gears, reduces the feeling of the lag .

Disabled Account

As above Phil........I went to 3.9 step-off and rear diff on my road/trackday Saph and will be doing the same to the Es Cos.......TOTALLY transforms the car (especially if you are running 18's).....you then realise how "silly" tall geared our Cossie's are with the standard final drive (3.6)......and 5th becomes a gear that is now usefull (i.e. not just for motorway cruising)

Porkie

iTrader: (1)

keeps you on boost more, gears are closer, car feels punchier and much more usable. I really can't see any downside.

It also gives your gearbox an easier life

TOP TOP TOP mod

I NEVER used 5th on track... and hardly touched 4th before I changed to 3.9 drive.

Now I have a 5 speed box insted of a 3 speed!

Anonymous

Yeah but Mike i think my spec now just stage 3 is lovely with all that grip....so all i'd be doin is upping the torque...ok it will suddenly drop off but only to what it is now....its just that shove from corners that a 40psi sike wouyld do nicely..LOL...remember i can do this to the current engine allowing the other engine to be big power

ian sibbert

11:1 and even higher on the focus enignes....I only wish we could run unrestricted....might have a chance against a 6R4 latest grp'a' cars with a T34 runs about 310 with approx 600 lbs/ft of torque....2.5 bar of boost....there is alot to consider in the specs when you look at grp'a' rally engines, wrc engines and good track car engines.....they are massively different....

Spiky

iTrader: (1)

Bosch-Man


i got a 3.9 rear diff for an esc cos here if ya need one

NUTS RuS

iTrader: (35)

Rally engines make USELESS road car engines.

Why on earth would anyone want one in a road car ??

It would need rebuilding every 1000 miles

GARETH T

stage three,,, new final drive and step of gears would be an amazing road car

Porkie

iTrader: (1)

Totally agree Gareth

Also a stunning and usable track car, HUGE fun, very fast without being a big budget, scary power, silly running costs monster.

Anonymous

Why would it need rebuilding every 1000 miles then? Your only giving it the torque level of a 500bhp motor and dont they go for 20k plus miles?

Mike Rainbird

iTrader: (3)

Phil,
I can only advise you not to do it, at the end of the day it is down to you.

I used to run a 34psi spike and hold only 26psi - my car would eat a T3/4 every 3 months . Pushing a T3/4 to 40psi is asking for trouble IMO. Don't forget that even the Grp A turbos were running maram shafts etc, and the WRC cars were running IHIs that are Ł6k a pop .

300bhp in an Escort feels slow as fuck . I'm telling you now, you WILL regret it .

ian sibbert

Tony is right in effect as the parts in a rally engine are 'lifed'....

Disabled Account

We ALL agree - BUT Phil's not taking any notice

Anonymous

...whats step off gears?

So an Escos std is 0-60 in 5.8 secs for large turbo what would a:-

320bhp stage 3 do 0-60

and

320bhp with monte torque say 500ft lb do 0-60

with this 3.9 rear diff on

In your opinion?

Mike Rainbird

iTrader: (3)

The gearbox / diffs would explode first .

Anonymous

you need a MUCH higher CR, the restrictor doesnt help with torque, it merely limits BHP, so if you take it out you have the same torque low down but more BHP up top.

Mike Rainbird

iTrader: (3)

And a melted engine, as the restrictor means single figure boost by 7k, which ALLOWS this high compression. Without the restrictor the boost would have to be backed off or forced to have the same boost curve as you have with the restrictor with air injectors.

ian sibbert

In my experience even an R&D gearbox cant take lots of torque for long....youd need a minimum of an FFD or X-trac transmission to acheive wot ur after....

GARETH T

what do you care about times phil,, your never going too have it timed

ive been in a few cars equipted with 3.9 final drives and they drive very very well

i do plan one day to have a go at 4.4 final drive in my car

you need step of gears for your transfer box because you cant really change the final drive ratio of the front diff so you do it in the transfer case

Porkie

iTrader: (1)

Step off gears and chain are what make the front diff a 3.9 ratio mate. You just need to change the CWP at the back.... OR buy Spikys

Anonymous

Mike your such a killjoy......do you tell your kid stuff like that..."DONT peddle to fast or you WILL snap the chain due to too much force thru a weak link"

Just answer the question assuming its been beefed up Anyway i thought Grp N cars were nearly std was they just std torque too?