Plenum increase worth it or not

[adyw]

Gents,
question.
The Engine mods are slowly on going so far it's
ACT induction kit
Mcgregor leads
Hose kit
new radiator (it needed it anyway)

Mega Squirt is planned over the winter
A new cam has been put off for now, (Wedding on the way funds being diverted)

The question is I have the opertunity to get 45mm alloy trumpets and a 72mm plenum, is it worth it in terms of power gains. I can fit it myself hence keep the price down. I was not going to put a ported manifold on as it is over my skill level, just keep standard manifold.
Is it worth it and if so does anybody have experience in gains achievable.
Car (griff 500) currently running 262bhp 301ft/lb

[Ballistic Banana]

adyw said:

Gents,
question.
The Engine mods are slowly on going so far it's
ACT induction kit
Mcgregor leads
Hose kit
new radiator (it needed it anyway)

Mega Squirt is planned over the winter
A new cam has been put off for now, (Wedding on the way funds being diverted)

The question is I have the opertunity to get 45mm alloy trumpets and a 72mm plenum, is it worth it in terms of power gains. I can fit it myself hence keep the price down. I was not going to put a ported manifold on as it is over my skill level, just keep standard manifold.
Is it worth it and if so does anybody have experience in gains achievable.
Car (griff 500) currently running 262bhp 301ft/lb

I unfortunatly didnt have mine RR'd before I put in the smooth induction enlarged plenum and V8D 45 alloy Trumpets. But i was pushing 278 after a RR session with MA and it did seem a lot more responsive over the whole rev range and not so lumpy low down aswell. I know just these extras didnt account for all of that but thought it may be worth mentioning.

[dnb]

Definitely worth doing something with the standard plenum and trumpets.

Mine made 320ftlbs and 265 bhp with standard induction + wild cam & VEMS ECU at the Growl. I could see a huge pressure drop from 3000 to 6000 RPM in the plenum, so this is costing a considerable amount of power. And the standard TVR trumpets aren't exactly ideal either...

[clive f]

I put carcon trumpets, insulator base and 72mm phlenum on mine and seem to remember it gained an extra 15hp, but the only real way to gain a significant power increase is to do away with the AFM altogether, a subject covered on here a lot in the past, but if your starting off on the mod route you`ll learn a lot in 12 months, don`t take one persons word for gospel, ask around and consider all your options

[OscarT]

I think a major factor you must consider first is do you want your engine bay to remain looking like a standard TVR engine bay or not.

If you do then you're limited to what can be done - this can be a good thing though - not as slippery a slope.

If not then where do you stop? Ultimately this route seems to lead to ditching the RV8 and sticking in a LS or even an AJP8 - a very long slippery slope indeed.

[eff eff]

[quote=clive f] ....but the only real way to gain a significant power increase is to do away with the AFM altogether, a subject covered on here a lot in the past.....

I've read those but I still can't get it all to add up, and I need to because I wan't to upgrade my engine and am struggling with which induction and managment options to go for. Maybe I'm thick! but I just looked at LS engines on the GM site and they have what looks a lot like a large single throttle on the front of the inlet manifold! If that's what it is, does it meter air flow by throttle angle or AFM, and how does that play against the multi-throttle options?

[clive f]

[quote=clive f] ....but the only real way to gain a significant power increase is to do away with the AFM altogether, a subject covered on here a lot in the past.....

[quote=eff][I've read those but I still can't get it all to add up, and I need to because I wan't to upgrade my engine and am struggling with which induction and managment options to go for. Maybe I'm thick! but I just looked at LS engines on the GM site and they have what looks a lot like a large single throttle on the front of the inlet manifold! If that's what it is, does it meter air flow by throttle angle or AFM, and how does that play against the multi-throttle options?] [eff/quote]

the easiest way to explain it is, you buy the induction pipe , this is 80mm bore, you put on a 72mm bore phlenum, BUT, the standard airflow meter has a bore or approx 53-54mm, so with this stuck in the middle of the intake system you can see where the restriction is!
Jools at trackcar has proved what a restriction over 150hp the AFM is.
there is the option of a larger AFM, but the most successful way on the market to date is to remove the AFM when replacing the standard ecu, and the chap you need to talk to about this is Joo at Trackcar Solutions, there are other options soon to be available, joo has something on the go, I think John Eals has another, and also v8 enhancements have got the twin phlenum design of dnb, as shown at the griff growl, soon to be tested, so hopefully lots of interesting developments underway.

Edited by clive f on Wednesday 10th October 08:16

[shpub]

eff eff said:

I've read those but I still can't get it all to add up, and I need to because I wan't to upgrade my engine and am struggling with which induction and managment options to go for. Maybe I'm thick! but I just looked at LS engines on the GM site and they have what looks a lot like a large single throttle on the front of the inlet manifold! If that's what it is, does it meter air flow by throttle angle or AFM, and how does that play against the multi-throttle options?

As I have TVRs with all three options...

LS1 has a big AFM to meter the air flow. I've removed it and the fly by wire throttle to run on throttle angle and manifold pressure. Using an MBE ECU though for both ignition and fuelling.

Big rover with 8 throttle bodies. THE way togo but very expensive and requires a complete revamp of everything. It does liberate power and makes hairy cams more docile. They are now in a simple plenum and force fed from a supercharger. Fuelling is based primarily on manifold pressure. I have gone through the multi throttle options and the reasons why they are used is that bigger throttles on the Rover plenum are physically difficult to implement and the large diameter can cause the throttle response to be a bit all or nothing. Yes you get the air flow but it is on or off. Smaller throttles but more of them can make the response better or at least easier for the driver to control.
Hence the old maxim: one throttle ok, two good, three better and eight nirvana.

Rover with big AFM and throttle. AFM is a limitation if chasing big numbers but going with a bigger unit means that ECU work is kept to a minimum. Removing it usually requires a different ECU to allow the better control to be acheived with throttle position or manifold pressure based fuelling.

The key point to all of this is that with the Rover system, simply bolting on different throttles in itself is not all of the story. The main part is then getting the ECU to exploit the new add ons and that is where the costs can quickly double or triple. The 14CUX ECU is fine but it is 30 year old technology and things have moved on a little since then. It also requires someone with the skill and experience to set them up so that the engine doesn't shrapnel itself.

Edited by shpub on Wednesday 10th October 09:19

[V8 GRF]

Pardon my ignorance but what do you replace the AFM with if you remove it?

[350Matt]

45mm trumpets are helpful but the thing is if you already have a 500 then the TVR 'trumpets' aren't actually that bad, Jools posted a while back saying he only found a few horsepower advantage when fitting 45mm flared jobbies over the TVR straight bits of pipe.

If you've still got the Rover intake of 38mm and longer pipes then this is where the real gains are found with a 45mm trumpet set.

A bigger throttle is definitely worth it tho'

Matt

[clive f]

V8 GRF said:

Pardon my ignorance but what do you replace the AFM with if you remove it?

you need to replace the lucas ecu to start with, then you have some sensors in the intake pipe which tell the ecu how much air is coming in, there is bound to be a very technical explanation which someone will offer shortly

[spend]

Wikepedia MAP (Mass Air Pressure) vs MAF (Mass Air Flow) probably has nice explanations? TPS is the common additional input.

Matt: I maybe wrong, but I thought those comparisons Joo made were blended base, shortened and original trumpets, the original trumpets too close to the plenum roof were a real no-no ? I got the impression that if you were going to the hassle of shortening & radiusing trumpets - the blended base was just as effective & less work. Didn't Joo end up with his own blended base in the V8S ( which I assume he did out of preference )

Dave

[shpub]

clive f said:

V8 GRF said:

Pardon my ignorance but what do you replace the AFM with if you remove it?

you need to replace the lucas ecu to start with, then you have some sensors in the intake pipe which tell the ecu how much air is coming in, there is bound to be a very technical explanation which someone will offer shortly

The amount of air coming into the engine can be measured/estimated by the throttle position/engine speed or from the manifold pressure(the engine is basically acting as an air pump. The only sensors I have are for air temperature and I measure the manifold air pressure after the throttles. From this information the amount of air coming into the engine can be calculated/estimated and the appropriate fuelling applied. This approach does require the mapping to be correct, especially to meet emissions and this will often vary from car to car. However, the AFM is not essential in what is effectively a custome engine/car specific installation.

[Johno]

In straight forward language . . .

A 72mm throttle butterfly will increase the amount of air coming into the engine by 25% for the same throttle position as the old butterfly.

The Lucas ECU is not capable of recgnising this and amending the fuelling accordingly and you will end up running lean. Which is bad, very bad.

It should only be fitted to engine running with after market ECU, or with revised chip, such as Mark Adams and then mapped accordingly . . .

A standard plenum will flow 300hp, and 72mm plenum will flow 320. These figures vary.

If you want one, get John Eales to do it for you, it's a lot cheaper than most go for on Ebay and it is a first class job.

[Johno]

350Matt said:

45mm trumpets are helpful but the thing is if you already have a 500 then the TVR 'trumpets' aren't actually that bad, Jools posted a while back saying he only found a few horsepower advantage when fitting 45mm flared jobbies over the TVR straight bits of pipe.

If you've still got the Rover intake of 38mm and longer pipes then this is where the real gains are found with a 45mm trumpet set.

A bigger throttle is definitely worth it tho'

Matt

I agree with you on this, except that the key help is surely in having the inlet manifold ported and matched to the trumpets. Just ticking trumpets on isn't going ot make a huge difference.

[adyw]

Thanks, gents all good reading definatly something to think about.
How can I contact John Eales ?

The question I now need answering is, with a 72mm plenum fitted will an after market ECU (Mega Squirt) then fitted will it make allowances for the increase in air intake with the AFM removed, hence not run lean

[Johno]

adyw said:

Thanks, gents all good reading definatly something to think about.
How can I contact John Eales ?

The question I now need answering is, with a 72mm plenum fitted will an after market ECU (Mega Squirt) then fitted will it make allowances for the increase in air intake with the AFM removed, hence not run lean

When you fit the Megasquirt, you can ditch the AFM you have currently and can then run with TPS and Air Temp as a minimum.

When the car is mapped on the rolling road, the fuelling can be adjusted to the new amount of air entering the engine. This will be done be checking of exhaust gases how the mixture is, rich or lean . .

Unless of course you go Lambda sensing, but I just do not see the need. . . .

For example, in my possession currently I have . . .

Bosch 4 hole pintle 30lb hr red tops
John Eales crank trigger wheel and sensor bracket
72mm throttle plenum
custom loom to incl. shift light and fan control
Emerald M3DK

I will set up the car on the standard injectors and plenum to make sure everything is running OK. Then I will add the plenum and injectors ready for Dave Walker to do the mapping.

As previously stated on the thread I want to keep the engine bay standard looking and therefore have stayed away from multi throttle applications.

However, if I change my mind, I will go for John Eales latest inlet manifold and individual throttle set up . . . Awesome but wave goodbye with set up etc to £3500k I reckon . . .

John Eales contact details . .

[e-mail]

http://www.rover-v8.com/JEEngineering/web.nsf/page...

[adyw]

Thanks for that,
I'm going along similar lines, keep under bonnet the same, Get the MS working then add 72mm plenum, and RR session
I'm trying to avoide inlet manifold upgrade unless I win the lottery.

[Johno]

adyw said:

Thanks for that,
I'm going along similar lines, keep under bonnet the same, Get the MS working then add 72mm plenum, and RR session
I'm trying to avoide inlet manifold upgrade unless I win the lottery.

Overall I would say that the 45mm trumpets are worth doing as long as the intake is ported and matched to them. It isn't as much as you might imagine and check with JE aout costs . . . Good luck.

[David H]

dnb said:

Definitely worth doing something with the standard plenum and trumpets.

Mine made 320ftlbs and 265 bhp with standard induction + wild cam & VEMS ECU at the Growl. I could see a huge pressure drop from 3000 to 6000 RPM in the plenum, so this is costing a considerable amount of power. And the standard TVR trumpets aren't exactly ideal either...

Is there a problem with your setup dnb? I would expect to see over 300bhp on a standard plenum on your setup.

Is the cam timing ok? Have you got a picture of the torque curve?