Chasing Torque

Well I have still been distracted by the Ds which is now finished and it survived the rolling road thrashing and is now pretty sweet for a 1970 car.
So the Gta hasn’t really been on the road much, but one day on the lift checking everything and it just just went straight through the mot, changed the holly’s jets for a leaner ones as it was to rich last year and it had a job to pass, plus after all these years of ownership i fixed the problem of the poor left had side handbrake which was someone had fitted a 10mm longer return spring on the cable which stopped the lever on the calliper pulling up all the way.
The interesting thing now is the mot brake test ways each axle before the test and the car had 1/2 a tank of fuel on.

Now you can see why you do not want to add any more Wt on the rear of the GTA, so when I swap the engine over with the 610 unit there is no way that extra 50kg of bits or that’s 2 bags of cement is going on the back of the car. I am hoping maybe an extra 15kg in the end, if I can’t achieve that I don’t think it’s worth fitting it as it will spoil the way the car handles, just to much Wt hanging out rear of the car.

Also that Wt is with a 16 stone + Mot tester sitting in the car doing the test.

[mettersl]

Hi Stuart,
Interesting information on the weights, will watch for that at my next MOT. Will the A610 engine be turbocharged and EFI?
Cheers
Lee

Hi Lee yes all of that but I am really worried about turbo lag, although I ported the exhaust ports and cleaned up the manifolds I kept the engine standard 610 as its an original engine, but one part of me I should have kept to my original plan an put the 9.1 pistons in with a small turbo.
The car is running really well and is vary quick on response and the thought of lag would get to me, not interested in top end speed.
One part of me is finish what I should have done big valve the old heads and higher lift cams in the old engine and keep it simple.

Do you know of a good hybrid variable vane turbo that would fit the engine probably the only way to sort out the lag problem as I have only just seen the 610 is 7.8 to one compression and the 2.5lt was around 8.5.
Do I just take the engine apart and put the higher compression pistons in, it’s a lot of work to put it in and be disappointed on response.

[mettersl]

Tony Smith has fitted a modern turbo to his 3.0 and John Law has engineered some new exhaust manifolds, both seem to give good results, I'm sure they will provide you with some details.
My recollection of the 610 when I last drove it was not bad lag as the boost system is better controlled than earlier generation Turbos like the GTA, but modern cars are so much better on this score.
I have some odd-fire (ATMO) hotter cams going spare if you are considering that route still too.
Cheers
Lee

Thanks I did some research a wile back and I think Garret made a turbo that the modification boys called the disco or something that was pretty amazing on spooling up very fast. My target I would like is 350/80 torque 2500rpm 230/50 hp 6000rpm.

Having said that I don’t no if the gear box can take that amount of torque that low down or the clutch.

Well I thought I was now at the end of modifications and repair but I just thought I would check the exhaust manifolds and I think they where welded up on Friday afternoon after a nice French lunch break.
So much extra metal sticking up it’s even cracked with the heat good for flow and turbo spool up, so more work to clean it all up.

Yeh, I think the exhaust manifolds are a poor situation, like an afterthought gone wrong.

Ok so I decided to another division experiment, along story but i came by a Mini Cooper D 1.6 08 which has the Citroen engine in it which was also fitted to a lot of other cars from Volvo to Ford etc.
As long as you keep up regular oil changes it’s a pretty amazing engine and very tuneable.
The Mini Cooper is about the same Wt as the Alpine 1100kg but it can make a lot of Torque, so after a bit off work this one is now running 300nm at 2700rpm and just under 140hp.
With the help off Miles in the mini we did two drag races 3rd gear 1500rpm foot down and the 2nd one 4th 1500rpm foot down, it was interesting the 3rd gear the Alpine would eat the mini but the most important one 4th the mini just disappears into the distance and left the Alpine for dead

This is the area that really gets me in road driving sitting behind a row of traffic doing 40mph in 4th as 3rd the engine is revving to much sudden gap appears you just want to pull out and foot down no faffing about changing gear I want immediate go and guess what a mini 1.6 just gets the job done so the point is the new engine build needs to achieve minimum off 300nm at 2700rpm or as I thought 350nm would be preferred. 250hp in 1100kg is fine.
Do I strip the engine down and go back to my original plan 9 to 1 compression pistons and a smaller turbo to achieve fast spin up and low down grunt, and the modern ecu should control this set up.
Having said that I’m not that sure that if I big valve the old engine heads and sorted the cams I would probably achieve not far off the target and the car would still be a simple engine setup.

[mettersl]

Phew...I thought for a second that you were going to do a mini cooper D engine transplant ....

My younger son is doing a lot of work on his 300 TDI land rover at the moment, he has just added a (self made) charge cooler in addition to its normal intercooler.
This has lowered on boost intake temperatures from 120 degrees to 40, improved spool up and mid range torque a lot (and the smoke is much reduced), all this is running 1.8 bar of boost. Its also had a load of other induction changes to get this boost level...all for a tow car... The benefits were much more than he was expecting.
You can probably get to these temperatures in Miles mini through the ODB port and the Torque app, I'm going to try that on my cars and see how they compare to Sons charge cooler. The Std GTA or even the 610 intercoolers are a bit of an afterthought, does anyone had any before/after numbers for adding a charge cooler.
It did make me wonder how much of the Turbo PRV improvements that are seen now are in the charge cooling as well as the other induction changes. It sounds like the core engine has lots of potential, more charge cooling might have a good effect too and is less work than different pistons.

I think you are right on the money Lee, the key would be getting the right size cooler to achieve the best temp result without being to big so that the the air volume after the tubo becomes to large as to create more lag.
Interesting I have just dugout my old Dino run and the Atmo engine was making 224nm at 3800rpm,
So would big valve heads and a good valve lift get that near 300nm at around 3000rpm and I would not have to bother with all that inter cooler stuff.
Does anyone have any figures for a big valve Atmo engine ?

I had the ART chargecooler on mine Lee, but then went back to the standard intercooler. I've no doubt the chargecooler works and works well (I think old David G threads pointed to at least 10-20 degrees drop) but I just felt that the extra weight, extra complication and additional 'drag' through the core sort of negated it. The standard intercooler isn't too bad, it just really only works when the car's moving, but I definitely think it could be improved with a newer design.

Mine used the barrel chargecooler in-line but then also retained the standard intercooler (normal trick of replacing the right hand plenum with the barrel). I think ideally if you did go chargecooled you'd remove the old intercooler and then just run a loop section of silicone hose to connect to the left hand plenum. That would save weight and remove some of the extra complexity.

I think the A610 engine loses a lot of the lag just because of the extra capacity. That extra 500 cc means you're already dealing with a 3litre, so torque is always there. Competing with any modern diesel is a bit of a lost cause though - GTA is geared higher in 4th than the mini, so it's going to need revs to keep up. My M3 will do 8000rpm and top end is razor sharp, but if it's caught napping a 320d will walk away from it. Modern diesels have a table flat torque curve from very low revs... I hired a Peugeot long-wheelbase van the other day for moving furniture. absolutely massive but the low down response was amazing. So much low down torque and throttle response, but nowt at the top-end. Sort of reverse M3 engine.

As far as I'm aware, variable vane turbos need direct control from the ECU to set the vane angles, I'm not sure whether there's any option to do that mechanically and otherwise you'd need a modern ECU to drive it I think Custard.