AJP8 rebuild upgrades?

[BCA]

Purely asking out of interest here, the Cerb will eventually need a freshen up granted, but with all the LS engine talk - I'd just like to get a vague idea as to what the options are out there for the AJP8s?

An LS conversion is quoted at circa 8k by Shpub, what exactly would that get you in terms of AJP rebuild opportunities?

[SimonSparrow]

Blueprinted engine and close ratio T5 gearbox?

[trackcar]

you'd need nothing like 8k to rebuild a very very good ajp8 Ben .. are you doing it yourself or contacting it out? Hopefull your will have thesteel crank even if it might be hte small journal with it being a gt block. I kno where you can get titanium rods made if you wanted those. Some nice pistons from the states - boostedls1 (ironically enough) will be able to spec and order those for you. Then its just head work really for anice N/A engine.

And if you wanted to spend all the 8k, a pir of turbos and aftermarket ecu For a home build thats easily an 8k engine, maybe some change left over ..

[shpub]

Let's make sure that we are talking the same thing:

8K for my SHPUB conversion include VAT and removing the old engine and fitting a new one. Drive in/drive out. The old engine can be sold for spares.
Many of the engine build prices are ex VAT and do not include the cost of removing and refitting the engine.

So when comparing, please make sure any comparison is made on the same basis.

In Jan Sprint there is mention of a complete Speed Six rebuild which cost £6.5K. The article then went on to say it cost another £2.5K to remove and refit. This did include a new clutch though.

[Boosted LS1]

trackcar said:

you'd need nothing like 8k to rebuild a very very good ajp8 Ben .. are you doing it yourself or contacting it out? Hopefull your will have thesteel crank even if it might be hte small journal with it being a gt block. I kno where you can get titanium rods made if you wanted those. Some nice pistons from the states - boostedls1 (ironically enough) will be able to spec and order those for you. Then its just head work really for anice N/A engine.

And if you wanted to spend all the 8k, a pir of turbos and aftermarket ecu For a home build thats easily an 8k engine, maybe some change left over ..

Oooh, the irony and I fancy building an Ajp and casting turbo headers.

[trackcar]

We are talking the same thing steve, for a n/a build to better than red rose spec it's easily under 8k drive in drive out, plus you get to keep the gorgeous ajp8 which has done 70k plus of track/sprint/hillclimb and road use in bens car and still going strong

[fatjon]

Even with a full rebuild, bigger injectors, custom fuel rails, twin plate paddle clutch, custom low compression pistons,copper gaskets, wire ringed liners 2 turbos, air/water intercoolers and custom inlet and exhaust manifolds I am nowhere near £8k. And I reckon it should do a tad more HP than a red rose....

[trackcar]

that ought to do it Jon

[SimonSparrow]

Ay carumba!

[BCA]

Some interesting points already...


Joo, I am not yet sure whether I would do it myself, depends how the other projects go I suppose. I am not yet sure how much freedom I will have with the body-off rebuild - so the in-board front suspension, single front lift off clam, Sagaris rear wide-track mounting points and rollcage additions may not happen. In all seriousness there are a fair few areas that I will be playing about with in order to enhance it, I hope it'll continue to punch well above its weight for the forseeable future as a result.

What is the ideal route for say a 420bhp-ish AJP8 to comfortably rev past 8krpm with the torque to match? I am not after huge amounts of power, the Cerbs always been terrifying, even with its factory 337bhp, more after a screaming, reliable, AJP8 that can take another 100k miles of abuse. Or, whats the best way to break 500bhp - I am less interested in this, but it seems to be the next biggest milestone...

I feel its been a bit of a shame to not have many people wishing to try a little harder with their own AJP's than go for the LS's reliability/ eventual cost. It just has me wondering what is possible if you throw £8k/£6k whatever at one? Fitting/removal doesnt matter to me, I'll do it, but for he sake of the argument lets say that costs £3k... so leaves £5k for a rebuild.

The twin turbo idea is an interesting one - I dont like turbos, I've had a fair few turbo failures on other cars, I hate cast iron turbo manifolds (they crack on smarts), I hate lag, I hate the related heat problems and the possibilities of losses of boost for various reasons - again something I have covered with Smart cars enough thanks! But thinking about a twin turbocharged (rear mounted would be my preference) AJP8 with the turbos spooled up and the bark of the V8 over the top is a delicious prospect. 500bhp has got to be easy from a low boost set up. Verrrry interesting stuff, maybe not for our car - but one to think about certainly!

It seems only fair to continue with an engine that has been so brilliant to us. It really is an absolutely fantastic engine - as has been pointed out, we're near as dammit at 80k miles of hard use - sprints, hillclimbs, trackdays, speed trials etc etc... its seen huge revs, been used daily in traffic and generally everything that'd test even stuttgarts finest. The whole car has, and in respect to the Cerb, its been pretty bloody bulletproof, I doubt many other performance cars would have taken things so easily. This is all before you consider the fact that it is ridiculously light, revs like a ba$tard, makes very good power for its capacity, sounds amazing at full throttle/overrun/idle (yes, I prefer the wierd V-twin off beat idle to the lazy RV8/LS woofle) - the fact that its reliable is just one hell of a bonus.

I just cant quite see the Cerb with an LS engine in it... Dont get me wrong, I love the conversion, I love the LS and I think those who believe you should "just buy a corvette" obviously have never looked at a Vette/the interior! Just maybe another TVR? A T350 or something. I am sure I'll do the conversion myself at some point with more major surgery - if one is going to use 'vette running gear, it seems appropriate to use thier idea and run a modified rear chassis to accomedate the gearbox. Especially as I dont think I'd want an LS engined TVR with any less than HUGE power and they're not exactly massively endowed in terms of traction.

So yeah, discuss!

[cupra20v.t]

have you seen this. probably more than 8k i imagine but you are keeping the ajp in the cerb.

http://www.pistonheads.com/tvr/default.asp?storyId...

[BCA]

cupra20v.t said:

have you seen this. probably more than 8k i imagine but you are keeping the ajp in the cerb.

http://www.pistonheads.com/tvr/default.asp?storyId...

Nope - I had'nt?! Timing or what?

With all due respect to Melling, I've got an AJP8 - I love it, I have no doubt that the man has some element of absolute genius to him. However, until the whole Melling cars/engines thing becomes a bit more transparent/proven - I'll just keep an eye on things. Alot of people are quick to sg him off, alot of claims are made - but alot of people talk absolute rubbish too. I will wait and see how this all plays out, but atleast theres hope for further life in the AJP8 unit yet.

[markh1]

I am very interested in this too.
How much power would porting and polishing the head release? and how much is it to get done?

[Boosted LS1]

FI on the AJP would look to be fairly straightforward. You'd need a decent piston and ring package and this provide an opportunity for custom designs. Compression needn't be to low but again you get to choose. Fit a Total Seal ring set and do a rebalance on the crank. Rod bolts may be improved. 'O' ringing the head would be a good idea as stated. I prefer cast headers for turbo applications and they can be heat treated or coated to make them look nice. I've never had a customer come to me with a crack in any headers I've cast. I do like to keep them neat and tidy to. I'm sure a blown ajp would be more then a match for the more routine lsx engines.

[BCA]

Interesting, Boosted - could it be possible to make decent power NA (420bhp+) with room for turbocharging at a later date??

Given a clean sheet/ AJP8 engine in for rebuild, free to do whatever you want within the confines of the Cerbera engine bay; what would your approach be?

[Ron Fellows]

fatjon said:

Even with a full rebuild, bigger injectors, custom fuel rails, twin plate paddle clutch, custom low compression pistons,copper gaskets, wire ringed liners 2 turbos, air/water intercoolers and custom inlet and exhaust manifolds I am nowhere near £8k. And I reckon it should do a tad more HP than a red rose....

holy sh:t Now were talking! What sort of power are you hoping for? Or should I say what is it expected to make

Edited by Ron Fellows on Thursday 12th February 17:45

[pole]

2 turbos! he is a crazy man!

[Boosted LS1]

BCA said:

Interesting, Boosted - could it be possible to make decent power NA (420bhp+) with room for turbocharging at a later date??

Given a clean sheet/ AJP8 engine in for rebuild, free to do whatever you want within the confines of the Cerbera engine bay; what would your approach be?

I'd look closely at the possibility of making a girdle to tie in the maincaps and block a bit better. I'd consider dowelling the caps as an alternative and I'd use decent studs throught. Next I'd measure up volumes and establish an accurate static compression ratio for the engine, which would allow futere decisions to be accurate. Weigh the rotating assembly and then consider custom pistons and pins. They will be stronger, lighter and have heat treatments like all my turbo pistons. A gapless file fit ring pack would be good as would taper wall wrist pins. Rods could be balanced end to end if needed. I've always used stock head gaskets without issues but you need really smooth mating surfaces. Wire rings could be of benefit in case a liner moves but a liner shouldn't be able to move. Externally, I'd cast a pair of headers. They could accept wastegates or the turbo's could have integral wastegates. Pick the turbo's according to air flow required, pressure ratio's and flow charts. You have to manage the extra heat produced when on full chat and when parked after a run, so radiator, airflow and shielding would have to be attended to.

As for 420 hp n/a without changing cams your only real option may be to rev or change external parts like induction. Revs increase risk (square laws and all that. Induction mods may be possible whilst still keeping turbo's as an option. You could run tighter squish and gain performance but that depends on what you have in the first place.

Guess that's about a weekends work then.

I'd cast something like this but it would be silver after coating and with a front facing flange.



Or this:

Thicker flanges and Tial wastegates underneath.

Edited by Boosted LS1 on Thursday 12th February 18:44

[fatjon]

The turbos and fuel system are scaled for a maximium of 800BHP, It's an experiment really as I wanted to test the possibilities of the engine before I start trying to apply what we learn to the Cerbera. That said, even in a rather boring Omega it will be good fun for the track days. Still a lot to do, the pistons only arrived yesterday. The bottom end is all rebuilt then we just dropped the engine back in loosely bolted together to make up the manifolds and layout the engine bay. For a cerb I think the turbos out from approach is the only viable option. Sealing the head gasket and preventing the liners walking around are going to be critical points. Dom at TVR power has given me a price for the mods to the liners and copper gaskets. Not too expensive at all, iirc less than £500 We will be limited by the T5 box but budgets won't allow anything stronger until later in the year. The diff is a BTR 78 series which is the same as the Cerb (??) so it will be a useful test of how far that component can be pushed before it goes with a bang. I have an Emerald ECU ready for the job but of course we will have to go from throttle angle based fueling to manifold pressure based fueling. Intercooling will also be a problem on the Cerb, hence trying out the air/water charge coolers, the plan being that we can mount the second water radiator in the boot on the Cerb version and the air/water units are much smaller than air/air ones. I think that it would be acheivable to do this on a Cerb with a budget of around 7k if you keep the boost down and stick at around 550BHP. If you go higher the box life expectancy will approach zero so quite a couple of grand will be added for stronger unit. Heat is the big question in turbocharged Cerb, only one way to find out though and with the right sheilding I reckon it can be controlled.

The pistons are a rather heavier and full skirted (540g as opposed to 480g) but the plan is to reduce the rpm limit to 6500 and make the turbos work rather than revving the engine to destruction. The more I looked at the slipper pistons the more it became clear that they just couldn't handle the power. The crowns are too thin and the skirts too weak to prevent distortion under boost.

Jon

[G20RG B]

fatjon said:

Even with a full rebuild, bigger injectors, custom fuel rails, twin plate paddle clutch, custom low compression pistons,copper gaskets, wire ringed liners 2 turbos, air/water intercoolers and custom inlet and exhaust manifolds I am nowhere near £8k. And I reckon it should do a tad more HP than a red rose....

Is this a Cerb engine bay??
And has this engine turned a wheel yet?

If not it's still to prove it's reliability.....something that can be said about an LS.

Good work with it though I really admire your skill in putting this together hope everything goes well with it.