BXProject

[docchevron132]

I really think the difference would be chuff all though.
The exhaust valves on the 21 head, and hence the recess in the pistons are smaller than the 8v head / pistons, so I'd say the drop in compression would be almost unmeasurable.
Given that if you used an N/A cam in the 8V head (as I intended to do) then the amount of time the inlet would be open would be just a touch narrower than the 21 cam timing I really think it's a non issue..

[Philhod]

Ah ! Thereby hangs the tail. I aint never seen inside a 2.1

[jayw]

D'ya know what?... This has made wonderfully interesting reading, but, WTF is the point of all this??? What's the idea behind the PSA junkpile hybrid???

(or did i yet again miss one of the twists or turns in this wonderous journey)?

[Bx Bandit]

Junkpile hybrid! What yer tryin' ter say lark!

[Philhod]

It's a BXP discussion Jay. A bit like that section in Citroenian,...., semantics.

[docchevron132]

Well, I came up with the idea ages ago, then the world and his fucking wife and dog decided to do the same, only AFAIK no-one actually has yet..

My reasoning was the 21 bottom end is a tad beefier, hence will take more BHP, but it's strangled by the woeful D12 head, hence my idea of using a 8V head (with bigger valves, ported and shit) on the D12 bottom end, Garrett T3 turbo, front mount intercooler, should be able to run 150 BHP all day nay bother.
That was my thoughts on the subject anyhow, but I never did fuck all about it sinc life and a 16v got in the way..

[Philhod]

That sounds a good plan that does

[mat_the_cat]

Well, I came up with the idea ages ago, then the world and his fucking wife and dog decided to do the same

Ah, but there are 2 types of people, sayers and doers.

Actually, as you haven't actually done it either I should probably add a third group - sayers who are actually more than capable of doing it if they didn't put ex wives and their Lance (the bus that is) first....

[docchevron132]

I dunno, maybe.. The bus has taken priority over most everything bar Kate of late...
I was keen to do it, even have the head built up with fuck off enormous valves ready to go,a nd had a block at one point, but then I discovered a few johnny foreigner types have put complete D12's in BX's, and the whole project seemed to be less appealing then. I like doing shit no-ones done before... and sticking an 8V head on a D12 in a BX would just be a variation of a theme now..

[Bx Bandit]

But Johnny foreigners have had to hack loads of stuff out their cars to get the job done, cos the turbo sits at one shitty angle and fouls the ARB or some such.

As I now have the lump and the 8v heads are plentiful, it seems a good project with oodles more torque than a 1.7 and I'd be blatantly pinching your idea! You could also have the car looking stock I rekon.

I'd rekon on too much lag with a T3 but that's purely an assumption. I found it surprising that the D12 had a smaller A/R turbo than the BX - it certainly got going much quicker but probably added to the strangulation effect at anything above 3500.

I'm loving driving the TD about, but it does lack low down grunt. I'm also in the 'I've too many cars' zone and wonder what's worth doing. Maybe a lovely Fraud Fiesta wouldn't drip so much oil and own me......

BTW Doc, if I do go the the D12 route, I'll stick a 'Intellectual Property Of The Doc Patent Plate' somewhere on the lump! You can also take her for a spin and tell me what I've done wrong if you like

[docchevron132]

bollocks mate. It might have been my idea, but I did fuck all about it, so I should care less.

I had planned the the early water cooled T3 nabbed from a maikonics CX with suitably fettled wastegate.. I did consider turbo lag but figured the fuelling possibilities with the 21 bottom end would be far greater and more controlable therefore having the grunt off boost to more than cope until the turbo came in about 1800 ish RPM.
The T2 I'm running on the 17TD now starts winding up quite nicely from 1700RPM but even at 1500 the boost is discernable.

[Bx Bandit]

Twin turbo the bitch then I rekon!
Actually, now I think about it, how do Twin turbo engines get around the choking effect of the smaller turbo after the bigger one takes over? wastegate the bitch?

I didn't think about the torque doing the job below turbo actually mate, the 2.1 seemed full of it.

I still got nothing at 1700 really, torque is ok but no turbo to speak of. I do think a 2.1 BX will make a nice car and a Bosch 2.1 pump comes up on ebay now and again at a reasonable £70 + p&p!

[Philhod]

2 Stage turbo's is the way to go. I was reading about a set up that had a smallish turbo that came on boost at 1200 revs. This is in line with a big unit that takes over at 2000 revs with a solenoid to open and shut the first one down, at appropriate moments.
There were no pics with this just an explanation, but it sounds interesting if somewhat complex.

[docchevron132]

similar tot he VW setup of turbo and supercharger really..

Can't say I was that arsed about a bit of bottom end lag in the setup I had in mind really.
Whilst balls out fun is ok for a lad, being as I'm a tad older and more sensible now (!) I tend to think of things like driveshaft / gearbox wear / damage..
Standing starts is more damaging than 250,000 of gentle cruising, so my aim really was to have a gruntier diesel that pulled like a class 57 and had some top end revviness if I wanted it..

[Philhod]

The unit on the Picasso has double angled vanes. This cuts a lot of the lag and gives grunt as well as being a simple system. There is a turbo on the Mundano that uses the Cit 2.2 motor, that is said to be very good too. It pumps out about 180 bhp, with I/C.
That is reported to have little lag and a lot of low down grunt, but I don't know what model it is.