F6a bits on F8b - just fishing for solid answers

[Sean]

Hi all... long time no posting!

I've searched the forums and the guides, but can't quite get what I'm after - I'm thinking of buying an f6a engine / frontcut to use as a source of goodies for the f8b. But, what exactly will be useable?

I believe the head may go on, but how easily and is it worth it?

Would the Turbo setup be of use, even if I stayed the carby route?

Will the EFI system bolt on to the f8b head, (hello Brayden - couldn't find any updates past 'sort of') and then would the engine management be of no use anyway and require an aftermarket jobby?

I realise most of this has been touched on, but just trying to confirm for sure if it's worth it... Don't really want to go the full install of the f6a - at least not yet.

Wouldn't it be nice if the head, efi, manifolds, etc all just fitted (maybe a little fiddling for clearances internal and external) and actually worked?

Tx!

[ceej]

Head will go on, but you will need a custom timing belt and head gasket. Turbo exhaust manifold will go on, and the turbo will fit also. And yes, it can be used with the Charade carby (thats how Brayden was running his). EfI manifold will bolt up, looking at Brayden's, it's a tight fit, but it will bolt up and fit in, however after market ECU is requiredl.

[Brayden]

Ceej is spot on, although with an F6A Alto exhaust manifold you'll need to relocate the alternator to the back of the motor with some custom brackets.

In all honesty having done the carby turbo and now EFI conversion on an F8B I think you would be far better off absorbing the cost and pain of buying a working F6A front cut and installing the entire thing. At least that way you have a turn-key engine that will work without a heap of extra work and stuffing around.

With hindsight thats probably what I would have done.

[jono]

Yeah, I think that would have been good to do as well but didn't have the capital at the time.

The inlet manifold is a b***h to put on (helps if you have small hands!)

I agree with the stuffing around though as I will have to spend a bit more to get it tuned properly, but I think I will wait till I decide to turbo it and just put up with its imperfections for now

But, I remember you saying Brayden that you can't wait to have a turbo EFI with an extra 200cc

BTW - is that exhaust manifold and turbo hard to find? Are you using a IHI or Garrett? Is IHI heaps cheaper, because a Garrett T12 are like $850 aren't they?

Gee, that turned into a long post, oops

[ceej]

BTW - is that exhaust manifold and turbo hard to find? Are you using a IHI or Garrett? Is IHI heaps cheaper, because a Garrett T12 are like $850 aren't they?

Gee, that turned into a long post, oops

They are as easy as sourcing most parts for Kie cars of the era. If you can get onto a source, they are easy enough to find. Just make sure you don't get the manifold for an F5A, been there, done that, wont work.

I think Brayden is still using the IHI RBH31 (sorry for speaking for you mate). They are no longer being manufactured, and the Garrett option is a replacement turbo, of the same size, but is considered an upgrade. Yes they are expensive for what they are, but they are one of Garrett's "Performance turbos". Personally, if I had the cash I would go down the GT12 route first time, but I don't, so the IHI is more for me.

[Brayden]

But, I remember you saying Brayden that you can't wait to have a turbo EFI with an extra 200cc

True, having that extra 200cc will spool the turbo faster, but the twinkie F6A is better designed and will handle more boost.
The bonus for me is that the majority of parts I have used can be replaced without having to search offshore.

Just make sure you don't get the manifold for an F5A, been there, done that, wont work.

F5A single cam turbo manifold would be fine. I have had a good look at a partially disassembled twinkie F5B recently and there's no way the manifold from that would fit though.

The turbo I am using is an IHI RHB31 (F6A variant) on a Jimny manifold. This has both good and bad points when compared to an Alto manifold. The good thing was I didn't have to relocate the alternator, but the bad news was that I needed a custom dump pipe and a narrow radiator had to be sourced. I'm not at all pissed off about that, mainly because the custom dump pipe is lighter and flows much better than the standard cast unit, and the new radiator is much more efficient than the old one! Cost is of course the only downside.

The GT12 is intended as a direct high performance replacement for the RHB31, however it does have slightly larger impeller and compressor wheels, plus it has a ball bearing design. I hadn't heard that IHI have stopped producing the RHB31 either, so perhaps ceej can confirm his source on that info?

At any rate I will be looking at purchasing a GT12 when my current turbo decides to throw in the towel, which I am hoping happens at about 15PSI. I do have a brand new K04 turbo in the garage though, so I might get a new manifold/dump pipe made to suit that instead. Depends on how flush for cash I am at the time.

[jono]

OK, so how much for a RHB31?

I think I might get a manifold made up by the same guys who did my extractors. Will I still have to get a smaller radiator like yours Brayden? And on that note, have you got the details on the radiator?

Thanks,

Jono.

[Brayden]

If you get the manifold built so that the turbo is in a better position than mine then you won't need to touch the radiator.

But enough of stealing Sean's thread.

[Sean]

If you get the manifold built so that the turbo is in a better position than mine then you won't need to touch the radiator.

But enough of stealing Sean's thread.

Steal away - it's all good info!

Brayden, did you end up sticking to the original head on your f8B and then fitting the bits around it?

[jono]

Yeah, agreed

Sorry Sean

[Brayden]

I kept the F8B head purely because everything pretty much bolted on, and at the time I had rebuilt the motor and didn't want to toss it away.

The F8B spins the RHB31 very effortlessly, which is just what I had hoped for - even with the front mounted intercooler. Down the track I suspect a twin cam head will be going on the motor though, just to extract the extra RPM I'll need for a larger turbo.
We'll wait and see how successful the EFI is I guess, but having now owned a Swift with a G13B twin cam motor I can tell you that the sound and feel associated with the tacho needle accellerating faster past 5000RPM is very pleasant! (As opposed to the F8B running out of puff at about 6k)

Jono, I apologise for my previous post, I wasn't having a go at you for stealing the thread, I just didn't want the topic straying from answering Seans questions.

[jono]

I knew you weren't having a go mate

I'm pretty keen to have an EFI turbo F8B, I think it will do me (for now ) Now, jsut one quick question, if I only want to run say 7psi, is there a need for an intercooler?

Sean, I recommend if you have the $$$ to probably go down the F6A route, for the reasons Brayden said.

Good luck

(Now to go find me a place which can give me some info a turbo!!!)

[Brayden]

I'd recommend even a small top mounted intercooler with a bonnet scoop for 7PSI. I ran mine without one and the plumbing between the turbo and intake manifold used to get extremely hot.
After fitting the front mount the same plumbing became cold to touch. I couldn't believe the difference.

[Sean]

I think I agree with you guys that if I want to go the efi route, fitting the whole f6a engine would be the go.

I'm still thinking about the carby option, though, especially as it may not quite be as expensive and a nice way to have a little more fun in the interim - and I too like to tow with my MB!

From what I can gather, though, buying a frontcut may be a good idea if I absolutely intend to transplant it down the track, but if I may not, just finding a suitable turbo, grabbing a charade carby (if I can find one) and the other bits might be a cheaper option?

Sean

[Brayden]

The carby setup will work out cheaper than almost all EFI alternatives, but the downside is the amount of stuffing around involved in doing manually what an EFI setup can do with a tweak of a map.

Fueling is relatively easy to get under control, but the distributor arrangement is a royal PITA unless you have the skills or contacts to regraph it.