Chimaera 4.0 tuning
Discussion
Looking for some advice.
I have a mint '98 4.0 Chimaera with uprated suspension, Tuscan brake kit and Spider alloys.
I'm now ata cross roads; do I sell the car and get something else, or do I go down the tuning route?
I don't want to pay £4k +vat for a supercharger kit.
My thoughts were either tuning the existing engine, or obtaining a good, used 500 engine and tuning that.
If I go down this route, what sort of mods should I look at for the 400 and the 500 engines, and what sort of costs?
Any advice will be gratefully received.
Andy B
RTZ62
I have a mint '98 4.0 Chimaera with uprated suspension, Tuscan brake kit and Spider alloys.
I'm now ata cross roads; do I sell the car and get something else, or do I go down the tuning route?
I don't want to pay £4k +vat for a supercharger kit.
My thoughts were either tuning the existing engine, or obtaining a good, used 500 engine and tuning that.
If I go down this route, what sort of mods should I look at for the 400 and the 500 engines, and what sort of costs?
Any advice will be gratefully received.
Andy B
RTZ62
Regardless of the engine size the achillies heal of the RV8 is flow through the heads, so once I was certain the basics like the cam (and cam timing) and ignition system were in good nick, I'd concentrate on getting as much air in the engine as possible.
So you're looking at ported heads, ported manifolds and modified trumpet bases, bored out/multi throttle plenums, removal of the AFM and re-mapped electronics using an aftermarket ECU. Some mods will be cheaper some will be more expensive, likewise some give more gains than others. You're best speaking to some of the V8 specialists out there like John Eales, V8Developments, ACT, Castle Race Engines to name a few, speak to a few folks see what is available, what benefits each package gives etc and spend your money with the company who you feel best at ease with.
You should be able to get 250hp and 270lb.ft out of a 4l quite easily without going silly, likewise 300hp and over 300lb.ft is possible from a 5l without re-mortgaging your house.
Regards
Iain
So you're looking at ported heads, ported manifolds and modified trumpet bases, bored out/multi throttle plenums, removal of the AFM and re-mapped electronics using an aftermarket ECU. Some mods will be cheaper some will be more expensive, likewise some give more gains than others. You're best speaking to some of the V8 specialists out there like John Eales, V8Developments, ACT, Castle Race Engines to name a few, speak to a few folks see what is available, what benefits each package gives etc and spend your money with the company who you feel best at ease with.
You should be able to get 250hp and 270lb.ft out of a 4l quite easily without going silly, likewise 300hp and over 300lb.ft is possible from a 5l without re-mortgaging your house.
Regards
Iain
Chassis 33 said:
bored out/multi throttle plenums
i know these work from what i have read on here...there is just one thing i keep thinking is a restriction.I was thinking of getting another plenum and welding two into one so you have two inlets...been done loads of times...but what gains are you going to get...the air feeding them is still going down a 72mm tube and through the AFM before it gets to the plenum...surely that will be a restriction.
and here we go - can of worms time.
shortening the trumpets...if the gap between the top of the trumpets to the underside of the plenum is the same area as the diameter of the tube how will that increase airflow...
I know loads of people have done the mod and say they have noted an improvement.
If you want a faster car, buy a faster car. I know you will have invested a lot of time and effort in the current car and may be reluctant to change, but it's almost always the most sensible approach. If that isn't an option for whatever reason, the next most economic option is to fit a bigger engine. If that isn't an option (or you already have the biggest capacity you can get), then tune the one you have using conventional means (induction, cam, heads etc). If that isn't an option (or you have taken it as far as possible) then consider forced induction, laughing gas etc. The further down this list you go the more time and money will be involved, the less reliable the car will be generally and the harder/more expensive it will be to insure.
andy-w said:
shortening the trumpets...if the gap between the top of the trumpets to the underside of the plenum is the same area as the diameter of the tube how will that increase airflow...
I know loads of people have done the mod and say they have noted an improvement.
I don't know, but I suspect the main gains from shortening the trumpets come from reducing the tuned length and hence raising the revs at which they come on song.I know loads of people have done the mod and say they have noted an improvement.
AFM being the bottleneck has been argued countless times. Throttle is a bit more complicated. You have to consider equating 1 large throttle with each cylinder sucking 1 after the other (bit of overlap but you should get the idea) with a nice steady pull of air to the plenum. Otherwise think of 8 TB's stopping & starting (air & petrol have inertia you know) as their cylinder wants to breathe, and individual TBs are quite small in comparison to the plenum TB. Getting even flow within the plenum is also quite tricky, not only re throttles 1/2/or 3 - but also the trumpets. It seems if you want pure top end power (where it should be IMHO) dump the trumpets and ream out the base. Smoothing & flowing is all well & good, but big holes with less restrictions seem easier to achieve in my simple grasp of things. FFS if wasted valves make a difference - it doesn't need a lot of imagination to see removing even small obstructions should have a plausible effect? Getting an even flow of charge to each cylinder is quite hard too, you need to study the firing order and look at how the ports overlap - then get a headache.. ad-infinitum...
You need remaps to make any sense of any of the above, hence the common rec. to get a proper ecu, (and ditch the afm) with mapped ignition into the bargain
Dave
You need remaps to make any sense of any of the above, hence the common rec. to get a proper ecu, (and ditch the afm) with mapped ignition into the bargain
Dave
RTZ62
You seem to be very swiched on to the economics and not exceeding a budget, hence your rejection of the 4K for supercharging, etc.
Bear in mind that modded TVRs NEVER sell well so don't be tempted to spend a bundle of money on 'upgrades' unless you're going to keep this TVR for a long time. You won't get your money back - in fact you would probably lose money for your trouble.
Keep your Chimaera as it is - if you want a faster TVR then as has been said already - sell your 4 litre and buy a more powerful TVR.
Modifying TVRs is fun and a challenge for the owner BUT a complete turnoff for future owners.
No-one wants to buy another man's ego-trip/penis-enlargement.
Jay
You seem to be very swiched on to the economics and not exceeding a budget, hence your rejection of the 4K for supercharging, etc.
Bear in mind that modded TVRs NEVER sell well so don't be tempted to spend a bundle of money on 'upgrades' unless you're going to keep this TVR for a long time. You won't get your money back - in fact you would probably lose money for your trouble.
Keep your Chimaera as it is - if you want a faster TVR then as has been said already - sell your 4 litre and buy a more powerful TVR.
Modifying TVRs is fun and a challenge for the owner BUT a complete turnoff for future owners.
No-one wants to buy another man's ego-trip/penis-enlargement.
Jay
Jay Ayegees said:
RTZ62
You seem to be very swiched on to the economics and not exceeding a budget, hence your rejection of the 4K for supercharging, etc.
Bear in mind that modded TVRs NEVER sell well so don't be tempted to spend a bundle of money on 'upgrades' unless you're going to keep this TVR for a long time. You won't get your money back - in fact you would probably lose money for your trouble.
Keep your Chimaera as it is - if you want a faster TVR then as has been said already - sell your 4 litre and buy a more powerful TVR.
Modifying TVRs is fun and a challenge for the owner BUT a complete turnoff for future owners.
No-one wants to buy another man's ego-trip/penis-enlargement.
Jay
I agree with your thinking but as a 450 Chim owner who has considered these options,the problem with buying a faster TVR is that a 500 isn't gonna have a significant enough increase in power.You seem to be very swiched on to the economics and not exceeding a budget, hence your rejection of the 4K for supercharging, etc.
Bear in mind that modded TVRs NEVER sell well so don't be tempted to spend a bundle of money on 'upgrades' unless you're going to keep this TVR for a long time. You won't get your money back - in fact you would probably lose money for your trouble.
Keep your Chimaera as it is - if you want a faster TVR then as has been said already - sell your 4 litre and buy a more powerful TVR.
Modifying TVRs is fun and a challenge for the owner BUT a complete turnoff for future owners.
No-one wants to buy another man's ego-trip/penis-enlargement.
Jay
And all the other TVR's that are quicker without a roof, use the Speed 6 which move maintenance costs into another league compared to the RV8.
Which only leaves moving away from TVR which i cant find anything else that compares.
Thanks for some great replies and suggestions. 
So, the concensus seems to be either move up to a Chimaera 500 (I can't see me selling this car to buy one, mine is too good an example to sell), tune it (but at what cost?) or buy a 500 engine.
Now, I have a mate with a Sunbeam Tiger (I know, I know) who has upgraded it from 4.2, via 4.7 to 5.2 litres and a proven 500+bhp.
He has offered to cast his magic over the TVR, and reckons that he could tune the 400 engine relatively easily (I still think that £ for £ I would be better off starting with a good used 500).
It would appear that there are a lot more tuning options available for a 500 (heads, exhausts, carbon plenums, TB's etc)
Any thoughts?
So, the concensus seems to be either move up to a Chimaera 500 (I can't see me selling this car to buy one, mine is too good an example to sell), tune it (but at what cost?) or buy a 500 engine.
Now, I have a mate with a Sunbeam Tiger (I know, I know) who has upgraded it from 4.2, via 4.7 to 5.2 litres and a proven 500+bhp.
He has offered to cast his magic over the TVR, and reckons that he could tune the 400 engine relatively easily (I still think that £ for £ I would be better off starting with a good used 500).
It would appear that there are a lot more tuning options available for a 500 (heads, exhausts, carbon plenums, TB's etc)
Any thoughts?
Jay Ayegees said:
Then improve your driving skills so thet you get more out of your 450 - sometimes we're too ready to seek more power when what we need is more skill.
Jay
Well i was just in a big reply explaining things but lets cut to the chase. Skills are fine thanks!. But the Chim is lacking in straight line grin factor now.Jay
Speed 6 is a quite different ownership prospect so IMO its spend money on the RV8 engine or sadly leave TVR ownership.. Though i cant find any other car that compares..
RTZ62 said:
Thanks for some great replies and suggestions.
So, the concensus seems to be either move up to a Chimaera 500 (I can't see me selling this car to buy one, mine is too good an example to sell), tune it (but at what cost?) or buy a 500 engine.
Now, I have a mate with a Sunbeam Tiger (I know, I know) who has upgraded it from 4.2, via 4.7 to 5.2 litres and a proven 500+bhp.
He has offered to cast his magic over the TVR, and reckons that he could tune the 400 engine relatively easily (I still think that £ for £ I would be better off starting with a good used 500).
It would appear that there are a lot more tuning options available for a 500 (heads, exhausts, carbon plenums, TB's etc)
Any thoughts?
My only concern about going 500 first is that as far as i can remember its a long stroke engine and isnt the most keen to rev.So, the concensus seems to be either move up to a Chimaera 500 (I can't see me selling this car to buy one, mine is too good an example to sell), tune it (but at what cost?) or buy a 500 engine.
Now, I have a mate with a Sunbeam Tiger (I know, I know) who has upgraded it from 4.2, via 4.7 to 5.2 litres and a proven 500+bhp.
He has offered to cast his magic over the TVR, and reckons that he could tune the 400 engine relatively easily (I still think that £ for £ I would be better off starting with a good used 500).
It would appear that there are a lot more tuning options available for a 500 (heads, exhausts, carbon plenums, TB's etc)
Any thoughts?
I could be way off but im not certain all 500's have cross bolted blocks either.
As i say i could be way off track but im sure some more technical engine guru's will smack my knuckles if im wrong..
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