Help!! 4.0HC Chim' 202BHP!!

[Golflion]

Had the 1996 Chim' since November2005.Came with full service history (at Brooklands TVR).Last service was in August of last year.
Always thought she was fairly fast but not upto full potential, so i had her on a rolling road at 'Tunit Dyno' in Chorley where the Blackpool gang visit.
She came out showing only 202BHP instead of in the region of 260ish which the mechanic thought she should.
His advise was to have a full engine service etc, but her last one was only in August.
Any advise on this would be helpful as i am unsure what the besty course of action is(don't want to pay for a service and its no better.
Is it something that could be simple to cure or do i need a doctor!!!!!
Would show print out but don't know how

[that daddy]

was that a crankshaft figure,normal HP loss is worn cam lobes on these engines,providing tuning is up to scratch etc.Not a major problem,ive read post's with much less HP....Oh check that foam air cleaner isnt clogged up with road grime,often overlooked.Good luck finding those horses.

>> Edited by that daddy on Saturday 8th April 12:23

[GreenV8S]

Rolling road measurements vary enormously so you can't read too much into an isolated figure from an unknown rolling road, but 200 bhp is a typical (corrected) flywheel figure for a healthy 4.0 on a typical rolling road.

[mongoose]

Don't panic!If the Rolling road was an honest one,ie not one to please the lax power brigade,then those figures wont be too far away i'd have thought.A good order 500 motor makes between 240-250 bhp on the one i use,so that gives you an idea of how much TVR differ with their original numbers.If your not too far away it might be a good idea to visit Julian at www.track-car-solutions.co.uk for a good comparison,and some good,freindly,experienced advice

[GreenV8S]

PS the mechanic who was expecting 260 bhp was probably confusing it with a 500.

[golflion]

How come the original BHP was shown on data as being nearer 275BHP yet the car is down at 200BHP. Really confused now.

Do you guys have any minor mods to help improve performance, as i don't particulary want to go over the top at this stage(maybe later!!) or am i best just getting a dyno test??

[GreenV8S]

You probably aren't down on power, the discrepancy you are seeing is the result of comparing figures that mean different things. The numbers you are quoting are about right for a typical 4.0 on a typical rolling road. If it really is an HC (rather than just a rebadged standard engine) then you might expect to get readings 15-20 bhp higher than that on a typical rolling road. But we have no way of knowing whether the RR you used is typical, and you can easily get variations of +/- 20 bhp between different rolling roads and different methods of measurement. So don't read too much into the numbers. What is probably more useful is to look at the shape of the torque curve to see whether that looks healthy. That is something that *is* directly comparable, and may show up lost torque due to engine wear or fuelling problems. But from the figures so far there's no reason to think there's anything particularly wrong.

[Mr Pig]

Hi, I have got the same problem. A 4.0HC which is producing 197BHP @ 5000RPM and only 210ft-lb @ 4000RPM.
The car has only done 23000 miles. A different rolling road confirmed those figures. TVR says my car is a genuine HC, so like you, I am wondering where my grunt has gone.
The knowledgable people at Scole Engineering believe the camshaft is shot. I understand this is a recognised problem so I am replacing the cam at the end of the month.
I will let you know how I get on.

[GreenV8S]

If you have a power curve then compare the shape against the curve for a typical healthy engine of the same spec with the same cam. This will show up various faults that affect the top end power. (It won't tell you what the fault is, but it will give you an indication that there is a fault.)

[sam gamgee]

Always thought it ludicrous to have to replace cam after such low miles...kinda annoys me, really. The one on my griff was done after only 50K. Love my car but "bl**dy TVR, sometimes....!!!

Dave.:smile:

[golflion]

Mr Pig,
let me know how you go on,this should be interesting.

[Graham]

I've seen quite a few 4ltr cars on the rollers and the norm is about 180 bhp at the wheels, so 202 at the wheels for a HC would seem about right to me...

260-280 at the wheels would seem to be a 5ltr figure....

[golflion]

Ok guys i feel alot happier than i was this lunchtime.

Thanks for all the comments.

As a small starter,K&N filter seems the way to go for starters,as you may well tell not been in this game long,but picking tips as i go along.

Any basic futher improvements are much appreciated.

[GreenV8S]

golflion said:

K&N filter seems the way to go for starters

Or you could upgrade from there to a high performance foam filter. Oh, wait, you already have one of those ...

[golflion]

Not good idea i take it.

Go on then put me in the right direction....

[trackcar]

202 as a flywheel figure sounds very plausible .. 202 at wheels sounds a bit high to be honest. You can do some very cost effective mods to get about another 15bhp .. but you might get some extra from some careful set-up on your existing engine for a start.
As you're only up in west yorkshire pop in and see me if you're passing slightly south and we can have a chat about what's available and routes you can take.
joo

[trackcar]

mungo said:

I thought TVR's claim for a 4.0 Chim was 240bhp and even then TVR are famous for being optimistic with claimed power output!

it's an HC which had the higher TVR hp rating. But you're right, as with most things TVR .. take with a large pinch of salt

[that daddy]

Anythings possible with manafacturers stated HP figures,I found out from my brother-in law dragracing/yank nut,in the sixties muscle car era those yanks dyno tested with nothing driven off crank.waterpump,alternator,etc,and still inflated figures,if you get a chance look at some of the claimed,chrysler, chevy,ford figures from sales gumpth,its laughable.May be it still go,s on.HE HE.

[vixpy1]

I've never had an HC that low too be honest, they usually push out 220-230.

[2 sMoKiN bArReLs]

Did they make HC as late as 96?