(This was posted on Lotussport.org, but received no concrete answers, just statements that raised more questions that were answered by statements that raised more questions)
I’m looking to upgrade the power on my N/A Exige (S2), I’ve sorted the handling side of things gradually over the years as I raced (with quite a bit of success) in the Stock class in our national sprint and hillclimb championship, which obviously precluded me from tinkering with the engine.
Those days are over as I’ve been bitten with the Time Attack bug I’ve run a first race test recently and more or less dominated the entire stock class (first time on a racetrack & in the rain) and closed just off the winner of the Pro 2wd Class winner, who runs a S/C CC Exige (S2) on slicks (I’m on semis), LSD, Close ratio gearbox etc…
My thoughts are to go for this class as it seems to be competitive, yet not insane (and I can be competitive whilst keeping the car road legal and usable).
As I’ve got most of the handling aspect of the car sorted (Nitrons, Antiroll bar, Induction/Exhaust, AP 4 pots, Big discs, Moved the front calipers to the rear, etc…) We now move on to MOAR power.
I’m thinking of the VF TVS S/C IC kit (http://visionfunction.com/product.php?id_product=14) + LSD, Clutch, lighter flywheel, Lower Final Drive and all the other incremental upgrades that come when the engine is being worked on.
Does anyone have any real world feedback on this kit (does it run well, does it deliver on it’s promises, can you drive around town in it etc…) ?
Has it been proven or should I stick to a Katana?
Will it kill my Gearbox on a weekly basis or will a set of stronger gears suffice?
Is it a reliable kit (this is a very important issue)
I’ve searched this forum but most of what turned up wasn’t TVS related (Or I’m a retard).
An oil cooler kit and stronger gearset should keep the gearbox in one piece, but the final drive can also be a weak link, the TVS setup should give more torque than the MP62 as it is larger but it won’t work as well at low revs for the same reason. you should also make slightly better horsepower than the MP62 as it generates less heat and has less parasitic losses for the same boost pressure, I have considered swopping to one from my MP62 in my S but have just never been prepared to invest the amount required.
You can just go Katana with a gearbox cooler and you should then be reliable, it also has a sensible upgrade path to have a charge cooler and 300+ hp if you feel you need more power later on but a Katana will give you about 230-240hp which is a reasonable step anyway
I’m prepared to invest in stronger gears, final drive & gearbox oil cooler. I am also happy to build a close ratio, strengthened E153 box over a period of say 6 months after install. I just can’t drop 20K on the car in one go whilst also getting my apartment built.
I know I’m getting ahead of myself, but what would a TVS with CC be good for?
The problem you run into is the need for stronger pistons after about 320hp or about 0.9 bar of boost. The ring lands will fail, this does not matter what SC you use, the standard gearbox is good for only around 190lbft of torque as it is the torque that kills it not the hp as such.
So as a rule of thumb stay at around 300hp on a stock engine and sorted gearbox and you should keep reliability, short ratios will make more difference than an extra 20 or 30hp and the E153 gearbox has completely the wrong ratios for a track car, they are way too long and it is way too heavy…
Yes unless you’re shooting for 400+ on a expensive built engine, the box really limits you to 320hp and doing stuff like E153 is one route but a lot of hassle for a 5 speed box.
Gearbox wise, put a laminova in with a weldon oil pump to cool the fluid, that’ll help extend it’s life.
Put a proper data-logger in the car and chase time through refining the build and yourself.
There’s no guarantee of gearboxes failing at xxx hp. Have changed one on a 240PP car after it ate 3rd gear. Know of one that did the same on a 190 NA. Luck of the draw, driving style, useage, etc. Too many variables to say that anything in particular will kill one.
The good news about a shorter set of ratios or final drive, is that you spend less time in 3rd gear. In theory all the other gears are stronger, as nearer the bearings so less misalignment on the teeth. Along with better acceleration obviously.
Remember the final drive. I made the big mistake of switching back to standard as the straight cut jubu final drive was driving me nuts on the road. Two track days later, and first session at Anglesey and took 5 teeth out of the standard final drive. Long way home on a flatbed. Another rebuild and fingers crossed. This is with 330bhp and 220lbft.
I’m a greedy bastard, and one that’s never really happy with what they’ve got… So, the way I think I’m gonna play this out is to build up the capital for a good CC MP62 conversion + LSD, Clutch, Flywheel etc and will make a judgement call at that point whether to hold out some more and invest in the gears and final drive in order to run the TVS with the possibility of 350ish BHP down the line.
Whilst the boy racer inside me would love a sequential, I don’t think it’s the best choice for day to day use. I also heard that start/stop traffic, engaging of gears under low loads and low oil temps doesn’t do them much good.
I’ll have to dig into the individual merits of the various gear sets and what they’re rated for before pulling the trigger.
