engine rebuild mileage?
Discussion
Gradual wear would also include a slight reduction in power you would expect.
Only really noticeable if you took a ride in a 400 with new cam and maybe piston rings at that mileage which should feel slightly more urgent than your own car. Hardly something to worry about as we might be talking 20 hp loss.
A well bed in engine might lack a bit of grunt but might have less friction at higher revs so in fact be almost as quick.
If your engines quiet it’s likely got no cam lobes left
Put a new cam in and 25,000 miles later it’s cam will be ‘ knocked off” a bit and loosing power. In the overall scale of things it means very little in my book if your car is a tourer.
A run on a known Dyno like “Joolz” will tell you most things in one go.
Only really noticeable if you took a ride in a 400 with new cam and maybe piston rings at that mileage which should feel slightly more urgent than your own car. Hardly something to worry about as we might be talking 20 hp loss.
A well bed in engine might lack a bit of grunt but might have less friction at higher revs so in fact be almost as quick.
If your engines quiet it’s likely got no cam lobes left
Put a new cam in and 25,000 miles later it’s cam will be ‘ knocked off” a bit and loosing power. In the overall scale of things it means very little in my book if your car is a tourer.
A run on a known Dyno like “Joolz” will tell you most things in one go.
Thanks for all the feedback. I haven't driven another TVR so I have nothing to compare to but now that I am used to the performance I do notice it loosing some grunt in the higher revs. Doesn't really bother me as I don't track the car, just for spirited B-road driving. I shouldn't imagine £4k for 20bhp extra would but that much more of a smile on my face. The idle can also be a bit erratic but I imagine that is more likely to be ECU or lama sensor? I spoke to TVR power who said that the cam should be changed every 40k miles. I was lead to believe that the RV8 is bulletproof and if cared for will go well beyond 100k before needing a rebuild...?
Cams can go at that mileage but I personally think that’s a low figure.
The problem with these cars is that they are not driven regularly enough, starting them to move out of the garage for washing etc does them no good at all.
A cam replacement although quite expensive can transform the car and bring some of those ponies back, the bottom ends are generally bomb proof.
I treated my old car to a cam change at 80 k and a few other goodies at the same time, I opted to change the crank shell bearings and oil pump gears too just for peace of mind.
The crank bearings were showing some signs of wear at this mileage but not excessive.
Tuning these engines is a very slippery slope, the best option if you do want a bit more go is to put a 4.6 in, which can be relatively easy and not too expensive if your the person doing the work.
The problem with these cars is that they are not driven regularly enough, starting them to move out of the garage for washing etc does them no good at all.
A cam replacement although quite expensive can transform the car and bring some of those ponies back, the bottom ends are generally bomb proof.
I treated my old car to a cam change at 80 k and a few other goodies at the same time, I opted to change the crank shell bearings and oil pump gears too just for peace of mind.
The crank bearings were showing some signs of wear at this mileage but not excessive.
Tuning these engines is a very slippery slope, the best option if you do want a bit more go is to put a 4.6 in, which can be relatively easy and not too expensive if your the person doing the work.
DoctorBonzo said:
Thanks for all the feedback. I haven't driven another TVR so I have nothing to compare to but now that I am used to the performance I do notice it loosing some grunt in the higher revs. Doesn't really bother me as I don't track the car, just for spirited B-road driving. I shouldn't imagine £4k for 20bhp extra would but that much more of a smile on my face. The idle can also be a bit erratic but I imagine that is more likely to be ECU or lama sensor? I spoke to TVR power who said that the cam should be changed every 40k miles. I was lead to believe that the RV8 is bulletproof and if cared for will go well beyond 100k before needing a rebuild...?
Both answers are correct. Powers are correct as Tvr use high lift cams.
Landrover engines are not using high profile cams hence the point they are bullet roof.
Your slight lack of power at higher revs might be due to cam lobes being worn so valves don’t open quite as far which will restrict air and fuel into engine.
It might not be that at all so some basic checks like a compression test might be worthwhile.
If the motor runs well i’d leave well alone unless you really want those few hp back.
At the end of the day a Focus with a big exhaust lol will be faster than many Tvr but won’t look or feel half as good, oh and you can’t take the roof off a hot hatch so I refrain from racing such cars off the lights and both my car and I are better for it.
If your cam is shown to be worn badly then a cam change would be worth it but I’d want to know how well the rest of the engine performs before making that decision.
I’d want a compression check and at least one end cap taken off my crank to check bearing wear before committing to any engine work on the top end.
ETA oh and oil pump gears checked as Belle427 wisely points out
Edited by Classic Chim on Wednesday 20th October 08:05
Thank you both for your comments. I'll ask my mechanic for compression test and to assess for engine wear when it gets services next month.
@Belle427 - when you say installing 4.6 is not big money. What are we talking about ££££?
I'm not worried about racing hot hatches off the lights or such, I just want to ensure longevity of the car and engine as I intend to keep it forever.
@Belle427 - when you say installing 4.6 is not big money. What are we talking about ££££?
I'm not worried about racing hot hatches off the lights or such, I just want to ensure longevity of the car and engine as I intend to keep it forever.
DoctorBonzo said:
Thank you both for your comments. I'll ask my mechanic for compression test and to assess for engine wear when it gets services next month.
@Belle427 - when you say installing 4.6 is not big money. What are we talking about ££££?
I'm not worried about racing hot hatches off the lights or such, I just want to ensure longevity of the car and engine as I intend to keep it forever.
I would just leave it alone, maybe do a cam refresh and inspect the crank bearings but you will probably find it’s fine.@Belle427 - when you say installing 4.6 is not big money. What are we talking about ££££?
I'm not worried about racing hot hatches off the lights or such, I just want to ensure longevity of the car and engine as I intend to keep it forever.
Used 4.6 engines are around £1000 but may need a refresh unless you find a good one which soon escalates.
Engine swaps are more suited to those that can diy it to save on the labour costs.
Aftermarket engine management is one of the best upgrades you can do to future proof but if you can’t diy it then your looking at approx £3000 for this to be done, this seems a lot but it is money well spent and can transform the driveability.
I’ve seen some guys on here with gains of 20 to 30 Bhp just from management upgrades and pro mapping.
Cam wear will reduce power and particularly at higher revs where the valves are not opening far enough the get all the mixture in.
The hydraulic lifters do an amazing job of hiding a duff cam so without a small amount of dismantling/inspecting (or and experienced rolling road operator) you or your mechanic will have difficulty diagnosing a duff cam. If you road test TVRs on a regular basis you may be able to spot it.
A compression test will find worn valves and rings but will not find a duff cam.
TVR cams are made of chocolate...everyone knows that.
Steve
The hydraulic lifters do an amazing job of hiding a duff cam so without a small amount of dismantling/inspecting (or and experienced rolling road operator) you or your mechanic will have difficulty diagnosing a duff cam. If you road test TVRs on a regular basis you may be able to spot it.
A compression test will find worn valves and rings but will not find a duff cam.
TVR cams are made of chocolate...everyone knows that.
Steve
LLantrisant said:
time to fit a new cam and definately a new timing chain..plus main- and big-end shells (easy to inspect first when sump if off)...and you should be fine.
if you are still happy with the power-output: you should do NOTHING!!
I’m not sure I’d advocate changing the bearings without having the crank at least polished first.if you are still happy with the power-output: you should do NOTHING!!
If the bearings are worn and copper is exposed, the rough crank journals would quickly send the new bearings packing, too.
DoctorBonzo said:
I haven't driven another TVR so I have nothing to compare to but now that I am used to the performance I do notice it loosing some grunt in the higher revs.
No matter what car you own or drive you will get used to it and it will seem like it is losing its edge after a while.If it isn't knocking, rattling or smoking and you are happy with how it drives I would spend that money on petrol and drive it more instead.
When you talk about loss of power at high revs, don't forget that the power curve tails off above 5200 rpm, and the torque curve maxes out at around 3500 rpm. These are still Range Rover engines, when all is said and done, so perform best in the mid-range. If you want a high revving sports car there are plenty out there, but it sounds like you are actually happy with a relaxed but spirited B road cruiser, that whips past people on a Sunday dawdle, and the Chimera does that job really well.
Hope you ok bloke, xDoctorBonzo said:
My Chim 400 has done just under 100k miles. 40k well maintained and regularly serviced under my ownership. I'm not aware of it ever having a cam replacement or a rebuild. Has anyone else done this sort of mileage without noticing any signs of engine wear?
As mentioned above I'd expect the camshaft to be well worn if still original at that mileage.I went for a camshaft change at 80k miles on my 400 as a prelude to going for a Canems install. Car still drove fine and pulled really well- but I hadn't driven many other examples to form a decent comparison. Anyway, further inspection discovered the camshaft was properly worn, the valve seals were shot, and a couple of piston rings had snapped. Ended up having a complete strip down and rebuild. I was genuinely quite shocked at the difference in driving experience afterwards.
My conclusion was that these engines hide any wear rather well. I guess the torquey nature of the power delivery, combined with light weight masks the driving experience, whilst the relative simplicity and low stress of the engine keeps it ticking along without spectacular failure? It's why I would now say to anyone new to the fold and looking for a Chim, to drive as many examples as possible, to improve the chances of experiencing what a healthy one should feel like.
Regarding going for more power- I wouldn't bother unless you can get a good deal on a replacement (bigger) engine. I used to obsess about getting more power out of mine, but the eye-opening moment for me was driving a Tuscan about 18 months after getting the Chim engine rebuilt. Stopped all silly thoughts there and then and allowed me to enjoy the Chim for what it is- a relaxed cruiser with plenty of torque and a stunning soundtrack.
Gassing Station | Chimaera | Top of Page | What's New | My Stuff