Tweaking the 4L .... suggestions please

[larrylamb11]

Want to tweak more power out of a Griff 4.0L engine (without upgrading to 5.0L etc.) and without pulling the heads ......
what sort of mods can i do to improve power? I assume cam change is the obvious choice. If so which cams are other people using? Can one upgrade the inlet side? Bigger trumpet base or strangler flap etc.?
Anything else that people are doing to get more poke

[k77-widow maker]

Well if mine is anything to go by.....

1) decent cam
2) a new ecu chip
3) large plenum trumpets
4) NOS

and before all of this was done, upgraded brakes.

End result, one quicker than normal pre cat.

[Guillotine]

check out Tim at

www.actproducts.co.uk

he advertises on here.

best option...buy a 500.

THEN modify with act!

OR...BUY a modified 500!!!

Starmist was touting his 500 recently, buy his and save yourself £10K! it's loaded with act stuff and has been sorted well.

doing it is half the fun tho

there's an old racers adage

Q
"how fast can you make it go?"

A
"how much money have you got?"



>> Edited by Guillotine on Monday 8th November 17:12

[2 sheds]

larrylamb11 said:

Want to tweak more power out of a Griff 4.0L engine (without upgrading to 5.0L etc.) and without pulling the heads ......

The heads are big limiting factor but you can gain a fair bit without changing them.
I have developed my 4.0l Griff to produce 45+ extra bhp from standard and this is using the TVR standard cam (TVR51) Although this includes stage 3 heads which probably worth over 20 bhp alone.

If you want simple quick fix mods, by this i mean without engine work, i would go for Tornado Chip , Trumpet upgrade & smooth bore intake pipes & injector cleaning & RR session , budget around £1200 for around 20+ lb ft extra torque.

Tim

[GreenV8S]

2 sheds said:

budget around £1200 for around 20+ lb ft extra torque.

The going rate seems to be about £100 per bhp, so on that basis this sounds like very good value for money. I had the ACT induction system, cam, heads and 'Mark Adams' Tornado and the result was a cracking engine. Mind you it set me back a good deal more than £1200!

[2 sheds]

I think things have really moved on in the last couple of years with bolt on mods.
As you go higher up the scale of tuning then the £100 per bhp is correct.
Tim

[Boosted LS1]

If you don't want to lift the heads then you have to consider a cam change and breathing improvements. A 218 or 218 hybrid from V8D is really good. I ran several dozen cams through my pc and the high power cams only gained a few extra bhp but lost huge amounts of low down torque. The 218 retains the torque plus gains power and I've seen it in quite a few tiffs. The hybrid is even better:.

You need to identify the cam you have.

[slikk]

You probably dont want to hear from a Chim owner, but for what its worth.. .. ..
218h race cam, carbon trumpet, billet sprockets (much tougher), tickle the ports a bit, and Voila! 250 bhp at the rear wheels, and very tractable indeed. Roundabout £1200.00 all in

[GreenV8S]

I hate you all! I guess this is the price I pay for being an early adopter. lol

[k77-widow maker]

GreenV8S said:

2 sheds said: budget around £1200 for around 20+ lb ft extra torque. The going rate seems to be about £100 per bhp, so on that basis this sounds like very good value for money. I had the ACT induction system, cam, heads and 'Mark Adams' Tornado and the result was a cracking engine. Mind you it set me back a good deal more than £1200!

hmmm....£1200 = 80bhp in my case......unless i up the size of the jets, in which case i could have 150 bhp...i love NOS!!!!

[larrylamb11]

Interesting thoughts ........ cam seems to be the favourite. Is it easy to identify the current cam? The engine is currently on the bench in preperation for partial strip + clean in readiness for upgrades. I am pretty handy with the spanners so will be doing all the work myself and am not averse to fabrication and modification (i.e. if it is better to make a new plenum with for example a Jag throttle body, then that is what i could do). As someone said above, bhp 'out' is related to cash 'in' and budget is a consideration. All further thoughts welcome.....

[Mark Adams]

Don't forget to have your injectors ultrasonically cleaned - save yourself the grief later!

They should be cleaned no more than two weeks before you are going to use them, because they can jam if you leave it longer than this.

[2 sheds]

Don't bother with enlarging the plenum, spend your time working on the inlet tracts & trumpets and as mentioned 218 cam is a good choice, but most important allow for a tuning session with Mark Adams.
The 4.0L does respond well to mods / tuning

Tim

[HarryW]

slikk said:

You probably dont want to hear from a Chim owner, but for what its worth.. .. .. 218h race cam, carbon trumpet, billet sprockets (much tougher), tickle the ports a bit, and Voila! 250 bhp at the rear wheels, and very tractable indeed. Roundabout £1200.00 all in

not that I don't believe you, but I think you might be a little confused on that point .

Harry

[slikk]

HarryW said:

slikk said: You probably dont want to hear from a Chim owner, but for what its worth.. .. .. 218h race cam, carbon trumpet, billet sprockets (much tougher), tickle the ports a bit, and Voila! 250 bhp at the rear wheels, and very tractable indeed. Roundabout £1200.00 all in not that I don't believe you, but I think you might be a little confused on that point . Harry

I have the rolling road printout in front of me as i type this. No confusion at all old chap.

[larrylamb11]

Yee-hah! 250 at the rear wheels i could definately live with!
Am now researching cams.....
As for upgrading trumpet base, does one need to go for bigger trumpets (45mm) and a ported inlet manifold down to the head? or do the inlet ports on the head need opening out as well?
When looking at bigger trumpets, should they be reduced in height?

[slikk]

larrylamb11 said:

Yee-hah! 250 at the rear wheels i could definately live with! Am now researching cams..... As for upgrading trumpet base, does one need to go for bigger trumpets (45mm) and a ported inlet manifold down to the head? or do the inlet ports on the head need opening out as well? When looking at bigger trumpets, should they be reduced in height?

Mine is running a 38mm jobby.Have to be honest, the rolling road setup was important, and i would advise budgeting for this.

kim

[19560]

larrylamb11 said:

Yee-hah! 250 at the rear wheels i could definately live with! Am now researching cams..... As for upgrading trumpet base, does one need to go for bigger trumpets (45mm) and a ported inlet manifold down to the head? or do the inlet ports on the head need opening out as well? When looking at bigger trumpets, should they be reduced in height?

Hmmm, remember HarryW's comments. 250 bhp at the wheels is about 315 at the flywheel - that's more than most 500s and his head hasn't been fully ported as the 500 ones are. Just an observation.

[Mark Adams]

I think we're just back to the fact that different dynos give different results. Most people using this TVR forum seem to quote Austec, Power Engineering, V8D, or John Eales dynos. These dynos are all known to broadly agree with each other.

One of the dynos I use is Mech Repairs, and on a car that reads 300BHP at Austec, you will only see 250BHP at Mech. This doesn't mean it is wrong - just different.

The engine in my car has been on all the above dynos several times, and this at least gives me a frame of reference and proves consistancy.

250BHP at the wheels on an unknown dyno cannot be interpretted without comparing it to a known reference. As an absolute number it is way higher than most well sorted 500s would show on any of our reference dynos, but it doesn't actually mean anything without a reference.

So nobody should be miffed about the numbers...

[2 sheds]

larrylamb11 said:

As for upgrading trumpet base, does one need to go for bigger trumpets (45mm) and a ported inlet manifold down to the head? or do the inlet ports on the head need opening out as well? When looking at bigger trumpets, should they be reduced in height?

If you are going to 45mm Ideally you should port the heads as well as the inlet manifold, or at least tidy up and polish, yes the 45mm diameter trumpets are normally 35mm shorter, if you want to phone me i can advise you re doing the work yourself i have no problem with that.

P.S totally agree with Mark, re dyno figures, once you know the engine spec it's not difficult to estimate what figures they would show at say Austec's rollers and in some cases figures quoted are imo very high, but they are just figures, only compare with your car if they have been measured at the same dyno.

Tim