The V8 Owners Forum -

My Griff has performed well on the rollers at the weekend, but I wonder what I can do to find some of the stray horses that should be lurking somewhere...

Headline figures are 319.5 bhp @ 5700 and 349 ftlbs @ 4000 at the flywheel.

I will post the proper graphs when I can scan them, meanwhile here's an excel copy.


What I've done:

Standard TVR 5 litre Rover v8 with cleaned up (virtually standard) TVR big valve heads. CR is 10.8:1
H404 cam from v8 Developments
I paid a little attention to detail when I built the engine - eg making sure the gaskets were the right size for the ports etc...
ACT long primary exhaust manifolds
Custom twin plenum split intake (each plenum flows air for every other cylinder) with a pair of 64mm throttle bodies.
Mappable ECU with sequential injection and ignition
Probably a few more things which I can't remember...
Mapped to run on 95 RON fuel

So what would you do to find say another 20 bhp at the top end?

Thanks.

Well you could put some decent fuel in it and adjust your maps accordingly.

Shell V Power would be good.

As your running 10.8/1 compression you must have compromised your timing to avoid detonation.

Should find you what your looking for, but I suspect your on a mission with the low octane stuff.

Kevin.

You can see the compromise in the power curve. It's only going to be 5 to 10 bhp from 99 ron fuel, and I can't buy it locally.

The air temperature at the top end of the dyno run was just over 40degC so there's probably some work to do there, since temperature and low octane fuel is a double hit to the timing I can use.

BTW can someone who isn't as daft as me move this to a more appropriate forum - I don't just want to know about electrical changes!

moved it to engines but we dont really have a tunning section which is where this really belongs I guess. If you want it somewhere else dnb then let me know.

You can get an additive to put into normal 95 ron fuel dnb. It's not the sh*** ones in garages though that do bugger all.

I believe it is the exact same thing that used to be in leaded petrol that isn't in unleaded fuel. I can't remember the name of the firm my dad gets it from but it's a chemical called tetra ethyl-lead. You can make five star fuel too

It is legal still I think. It does work out a little more expensive though than decent forecourt fuel and probably a little toxic if you don't handle it properly

Andy Frost reccommended Power Pour to me.....Ive read about it, but still not conivinced as to its benefits.

Maybe it would be worth a try ??

320BHP out of that engine is good Dave. You will recall when you met my late friend Matt at the griff growl a couple of years ago he pulled around 280-290 on a std engine, apart from MS and EDIS.

What about forced induction?

With the mods Dave has made personally would have hoped for somewhere near the TVR quoted figure (340) for that engine.

My std 4.3 from a Griff was making around 275 in std trim other than Tornado chip after being setup by Mark Adams at Mech Repairs. It also had the tin gasket replaced by the thicker one so my compression ratio has been reduced. Its not the BV version either

If you take 275 / 4.3 * 5.0 comes out to around 319 which suggests Dave's engine is performing to a well tuned 5.0 Griff.

Appreciate all rollers and engines are different so could it be the rollers are reading low.

I use NF octane booster in the Impreza. This seems to work, but it's a bit expensive for a car that only needs it in the last 1000 RPM. Maybe some form of water or methanol injection would work?

Forced induction is on the wife's "banned list".

My Griff was performing significantly better than the standard Griffs on the day of the test. The better tuned std 500s were making 270 to 285, and produced a better torque spread than the 4.3 engines (but similar bhp) A special JE 5.2 with loads of mods made 318, so I don't think mine's particularly bad.

Mark Adams witnessed my run and thought it was OK, although I could probably get a bit more out of it if I tuned the top end on the rollers... Maybe the easiest thing to do would be to book a couple of hours on the rollers somewhere.

Surely you mean the CR increased when you switched to thinner tin gaskets?

And yes, I was hoping to be a bit closer to the 340 mark. The rollers seemed to be reading OK. A supercharged Jag made within 1hp of the book figure, although a TVR Sagaris only made 312 bhp.

r2d2hp wrote:My std 4.3 from a Griff... It also had the tin gasket replaced by the thicker one so my compression ratio has been reduced. Its not the BV version either

Have you asked Dom if tin gaskets 'could' be fitted to a 430. The wire rings would just not work with a tin gasket - they should all be composite with copper fire rings. TVR made the TVR heads all 28cc with composite gaskets before LR did, the development paths are not the same.

You may well have had tin gaskets - but it would require at least the wire rings skimming out - so not standard? TBH there is not a lot of valve clearance on the 430, it seems to have the highest compression of the TVR engines I've seen inside?

I'd have thought you should make more power than 320 if the claim of 10.8:1 is accurate Dave (500's are typically only @9.5:1 IIRC)? Rob may tell you if the H404 is not really suited to it, but generally the good TVR's respond extremely well to raised compression from what I've seen.

Hi Spend,

By tin I should have said copper and they were replaced by composite when I took them off to replace a snapped rocker cover screw that had to be spark eroded from one of the heads. The heads did and still do have the ring in them.

So my compression has definitely reduced due the gasket thickness increasing from copper to composite.

dnb wrote: Forced induction is on the wife's "banned list".

Fit turbo and just tell the wife that it's air con to make her more comfortable when she is in the car. You're just thinking of her.......

The 10.8 may not be accurate if you are right about the 9.5:1. I was told the CR of my engine was 10:1, so calculated the tin gaskets would give 10.8. If it really was 9.5:1 then it would only be around 10.2

I wonder if the ignition timing is just too conservative. At the top end it was only 25 degrees, and there wasn't even a sparkle of det.

Ah, Ben's old car penny drops!!!! Yes I seem to remember Ben bit the bullet and put solid copper in (You do have V8D heads with proper 'ultra' big valves IIRC). Why didn't you reuse the copper? - I'll have em off you if you don't like them :bindiver: The original copper ringed composite gaskets were same as 'normal' composites so you should be back to standard (in regard of compression) Ask Ben he may remember but I think the copper he used were skinnier so actually increased compression over standard - I did wonder if that may be why you had such a nice result (even for a BV). Hope Ben was pleased as well he certainly deserves some credit for it, do say hello from me if you see him

ppyvabw wrote:

dnb wrote: Forced induction is on the wife's "banned list".

Fit turbo and just tell the wife that it's air con to make her more comfortable when she is in the car. You're just thinking of her.......

My wife's a petrolhead, and almost an engineer (software, so maybe it doesn't really count ) She'd notice, and then she'd utilise my intestines as hoisiery accessories.