How much power in a +8

[StardustV8]

Hi there

Just popped in from (hold your breath) the TVR board. Im running a 400 Chimaera (3950cc RV8) and im having a wee chat about power.

See i recon the TVR unit is just a rangey 3.9 with different manifolds and at best a different cam. TVR claimed 240 BHP. Mine has done 57k and on my own maha 2000 rollers made 187 BHP at 4800 RPM. Interestingly range rover engines of the same ilk produce 175-180 BHP @ 4750 RPM. (see where im going).

Ive had the heads off and they appear exactly the same as the rover sd1 vitesse heads. Im not getting much sense out of the tvr lot as they are quite defensive. I would like more power but everyone i speak too....TVR Power, RPi, V8 developments etc etc say thats normal.

What do you get in yours and what is the factory spec?

Thanks in advance you lovely lot...........SDV8

[Bartell]

StardustV8 said:

Hi there

Just popped in from (hold your breath) the TVR board. Im running a 400 Chimaera (3950cc RV8) and im having a wee chat about power.

TVR claimed 240 BHP. Mine has done 57k and on my own maha 2000 rollers made 187 BHP at 4800 RPM. Interestingly range rover engines of the same ilk produce 175-180 BHP @ 4750 RPM. (see where im going).
What do you get in yours and what is the factory spec?

Thanks in advance you lovely lot...........SDV8

TVR did work on their engines. Their 5L is a good setup.

However, TVR is infamous for being very optimistic in all their Rover V8 BHP claims. Your guesstimates on your power are much closer to the truth. Did you test at the rear wheels or the flywheel?

The most powerful stock Plus 8s are from years past. Even their 4.6 were fitted with 3.9 fueling, producing a mildly torquey engine but lower bhp figures than rover stock and an overheating problem. This can be cured with proper chipping.

BHP ranges can vary with the block and fueling system. Tell me what you have and I can make some suggestion depending on how high you wand to go, your budget and the reliabilty factor.

James

[TimAla]

I have a 4.6 with extrapolated flywheel bhp of about 270. It was modified about six years ago, and I can't remember what was done, but there wasn't much to it. I'd post the dyno graph if anyone could tell me how.

[LE52 MOG]

I have a 2002 4.0 Gems +8 which has been re-chipped and runs @ 205 BHP. I seem to remember the factory quoted 190 BHP as standard.

[Bartell]

TimAla said:

I have a 4.6 with extrapolated flywheel bhp of about 270. It was modified about six years ago, and I can't remember what was done, but there wasn't much to it. I'd post the dyno graph if anyone could tell me how.

That would have been DEEP modifications..or an interesting figure used for the extrapolation.

Of course it is possible with a lot of money, performance chips, Stage III heads, some sort of ram effect for the intake, FAST road cam, exhaust porting, big bore twin exhaust with branch manifolds, free flow air filter, flared trumpets and preferably no cats.

LE52 MOG said:

I have a 2002 4.0 Gems +8 which has been re-chipped and runs @ 205 BHP. I seem to remember the factory quoted 190 BHP as standard.

You may be modest. 183 is the real standard (never believe insurance salesmen, car factories or performance tuners.) But if you have the right chips, 205 is yours with ease. More is possible.

James

[Bartell]

TimAla said:

It's possible the extrapolation may be off if the Morgan has significantly lower frictional losses than the average.

If that was the case, then your rear wheel figure would be closer to your flywheel reality not significantly higher as you are suggesting. However, the reality of a trad power transfer is exiactly the opposite. Big losses from flywheel to the rear wheel. One needs deep modifications (but sensible) to improve that.

That being said those mods will have you showing a tail to any other model.

TimAla said:

I'd definitely like to supercharge it if it's practical, as talking to other Morgan owners over time, quite a few would consider it if the package price were right.

Are you referring to Turbo or Super charging? Is your car on carbs or EFI?

There is plenty that can be done..but unless you wish to compete with kit car dragsters once a month and trailer it everywhere else, there are smarter options.

Hard to advise. Need to know where your car is at now. Cam, exhaust, flywheel, suspension upgrades, chips and which..intake, airflow.

James

[StardustV8]

Hi, yes as a Motorsport Engineer I am very familiar with how to tune engines and what is available for the RV8.

I am trying to find the actual norm for a 4.0 (3.9 with longer block registers) and compare it to what TVR claim.

TVR claimed 230-240 BHP for a 4.0 and 280BHP for 4.0HC (hahaha).
However on the face of it I can not see any difference to the standard pre 94 classic RR RV8 3.9! Yes I imagine the cam profile is different and the fueling and load sites on the EPROM chip of the ECU is different but apart from the exhaust and the longer intake pipe its the same. Not enough to give another 50 BHP in my opinion.

Now my car made the 187 BHP figure at the the flyhweel based on around 140BHP at the wheels and a calculated drag (by the rollers) of 47 BHP.

The figures are pretty much spot on for a standard engine meant for a RR 3.9 running Lucas Hotwire and standard FPR and mapping etc etc.

If this is a true reflection of the setup then fine, but if the engine really should make more than im happy to spend money to try and recover it.

New FPR
New cam, followers, pushrods
New injectors

I know the ignition side of the engine is fine as I have had it on my crypton analyser and the outputs at the coil, plugs and leads are fine. the injector pulse rates are fine and so are the waveforms from the lambda probes.

Once I get the engine running properly (or comfrim that it is) then ill look at tuning it.

Plenum
Trumpet lengths
Air delivery
exhausts
matched cam profile to the above
maybe a modified head and valves
rempapped ECU for the above
etc etc

I really want to identify whats normal first tho.

I was hoping one of you knowledgable lot might say "yeah about 190BHP is stock for a normal 4.0l on Lucas"

[GreenV8S]

I'd expect to see around 195 bhp for a cat and a little over 200 for a pre-cat. The power figures you're quoting are a little low (and peaking slightly lower than typical for a non-HC cam) but broadly in the right range for flywheel figures for a normal non-HC 4.0 in good condition. You're about 10 bhp down, but that could be accounted for by calibration differences in the rolling road or the engine being slightly out of tune.

Edited by GreenV8S on Saturday 22 November 14:20

[Bartell]

StardustV8 said:

Hi, yes as a Motorsport Engineer I am very familiar with how to tune engines and what is available for the RV8.

That's great. It will make this much easier.

StardustV8 said:

I am trying to find the actual norm for a 4.0 (3.9 with longer block registers) and compare it to what TVR claim.

TVR claimed 230-240 BHP for a 4.0 and 280BHP for 4.0HC (hahaha).
However on the face of it I can not see any difference to the standard pre 94 classic RR RV8 3.9! Yes I imagine the cam profile is different and the fueling and load sites on the EPROM chip of the ECU is different but apart from the exhaust and the longer intake pipe its the same. Not enough to give another 50 BHP in my opinion.

TVR has long been notorious for their bhp claims. Many have proven them to be incorrect. You have just joined that club

StardustV8 said:

Now my car made the 187 BHP figure at the the flyhweel based on around 140BHP at the wheels and a calculated drag (by the rollers) of 47 BHP.

That is low but not abnormal. The figure you use for your flywheel to rear wheel loss likely high. Morgans are non-efficient in transferring power and the dynos show a 21-22% loss. You are indicating a loss of 25%.

If we were speaking of a Plus 8, your 140 bhp would mean 179 bhp. However, this is what one should expect for the stock setup after a few years. The later GEMS 4.0 (2000-2004) left the Factory new at 183 bhp. (LR is not as bad as TVR but they were known to be optimistic on their power as well.)

StardustV8 said:

The figures are pretty much spot on for a standard engine meant for a RR 3.9 running Lucas Hotwire and standard FPR and mapping etc etc.
If this is a true reflection of the setup then fine,

Confirmed. Your engine is putting out what it should with the existing setup.

StardustV8 said:

but if the engine really should make more than im happy to spend money to try and recover it.

No need, you are running as they made it to run.

StardustV8 said:

I know the ignition side of the engine is fine as I have had it on my crypton analyser and the outputs at the coil, plugs and leads are fine

None of the Lucas ignition systems are great. They deliver low grades sparks at best and age poorly. However, there are easy upgrades available.

StardustV8 said:

Once I get the engine running properly (or confirm that it is) then ill look at tuning it.

Now THAT sounds like fun! Much is possible. Depends what you want and what type of driving you like.

Plenum - What do you have in mind? Not a twin or triple plenum I hope.

Trumpet lengths - Shortening them does not produce much effect despite the hype. You would better to look to Superflares (250£ +).

Air delivery: You mean a bigger MAF or a free flow air filter? The first forces you to go aftermarket is very fiddly and 90% unsuccessful (appr. 550£) and the second is the cheapest (22£) extra (4-8) bhp you will find.

exhausts: Excellent. a BIG power producer. The stock cast manifolds are very restrictive. Figure 1600£.

matched cam profile to the above; Sure but it is easier to go with something with a track record. If you buy something good off the shelf it will be 300£. Ground to a personal specification will cost more of course.

maybe a modified head and valves: You can stage your heads for a lot of money. Stage III would be 800£ excluding core charge). I have staged heads. Not super helpful on the dyno. The basic head design leaves little that can be done to them.

However, there are the new Merlin heads that are wonderful..but I am not sure you would do them justice putting them on a 3.9.

rempapped ECU for the above etc etc: Great chips are available. Again it depends how crazy you want to get. A great chip for a Hotwire is 375£. You can have one made for you by an expert on the car of course. (1000£)

Cheapest way to more power is swapping in a bigger capacity. stock 4.6, 4.8, 5.0 (which is an excellent TVR modded engine), 5.2, 5.5. Best idea is a new 4.6 (1100£+). That will give you what you want and is a much better base to begin. Capacity s the safest route to more power.

StardustV8 said:

I really want to identify whats normal first tho. I was hoping one of you knowledgable lot might say "yeah about 190BHP is stock for a normal 4.0l on Lucas"

I have. Consider it confirmed.