Best way to big power, turbo 4 or big V8?
Discussion
Just asupposing someone wanted 300bhp plus in their kit car, and both the options mentioned in the thread title could be accommodated if need be. I wonder if any members of our committee would care to put forward their feelings on this subject?
I personally am leaning toward the turbo option, which considering the increasing sophisitcation of turbochargers and their control systems would seem to offer a better match to continually varying driver demands.
I personally am leaning toward the turbo option, which considering the increasing sophisitcation of turbochargers and their control systems would seem to offer a better match to continually varying driver demands.
nissan 200sx trubo engines and boxes, eithe Ca18 or Sr20, 300hp is realtively easy and cheap. RWD box as std and narrower then a V8 (may effect choice if a narrow chassis). have seen them fitted to 7 Types before although the intercooler plumbing needs thought to do neatly.
VAG 1.8T again 300hp no real problems, although they are all FWD as std so you will need to find a gearbox. Plumbing again is the only real headache.
Cossie turbo 4 pot. again been done 100s of times. Not the smallest or lightest 4 pot, but 'off the shelf' availability and well trodden path make it a good choice
not really into V8s sorry
VAG 1.8T again 300hp no real problems, although they are all FWD as std so you will need to find a gearbox. Plumbing again is the only real headache.
Cossie turbo 4 pot. again been done 100s of times. Not the smallest or lightest 4 pot, but 'off the shelf' availability and well trodden path make it a good choice
not really into V8s sorry
trubo power delivery along with a clever ecu, can give drivability benefits as the boost can be varied during the transition from off/on boost,to smooth it out. also the turbod motors tend to be quite soft off boost for pootling about town. V8s with 350ft/lb torque from idle is hard work in a 500kg car
300bhp in a kit car for me would be best arrived at using an supercharged 4 pot IMO
I went from a BEC to an Evo VIIRS and although mighty quick, I'm finding the engine to be les fun than an NA lump. You lose a lot of the mid corner adjustability as a lift off to tighten the line sees the boost lost and there is that hesitation before boost is restored. I would find this very annoying in a very light kit car where throttle adjustability is part of the charm. At least with an SC, it is on boost all the time.
Conversely a 300bhp V8 is adding weight unnecessarily as you easily achieve 300bhp through lighter means.
I went from a BEC to an Evo VIIRS and although mighty quick, I'm finding the engine to be les fun than an NA lump. You lose a lot of the mid corner adjustability as a lift off to tighten the line sees the boost lost and there is that hesitation before boost is restored. I would find this very annoying in a very light kit car where throttle adjustability is part of the charm. At least with an SC, it is on boost all the time.
Conversely a 300bhp V8 is adding weight unnecessarily as you easily achieve 300bhp through lighter means.
Audi A4 1.8 turbo would give you a happy 300bhp with transaxle arrangement for mid engine or the quattro for 4wd. Then of course you have the V6 twin turbo.
I would go that route as they are modern and readily availabe from breakers in the uk. The tuning potential is vast and well proven.
I would go that route as they are modern and readily availabe from breakers in the uk. The tuning potential is vast and well proven.
4 bangers just dont sound distinctive enough considering the car is going to be your toy/playthnig.
why have the toy sound exactly the same as your daily driver.
go for a bike engine, or anything with more than 4 cyl's
although.. if you can get ahold of a RR/Jag SC v8.. snap it up and bolt it in!
why have the toy sound exactly the same as your daily driver.
go for a bike engine, or anything with more than 4 cyl's
although.. if you can get ahold of a RR/Jag SC v8.. snap it up and bolt it in!
Depends upon what you want really.
Lazy power delivery from tickover with huge bags of torque off set by potentially weighty cast iron block but simple internals. (SBC/SBF).
Or revvy engine with power made further up the rev range in a potentially lighter but more complex block. (Turbo)
If it's going in a lightweight kit car then IMHO big hp numbers are not necessarily a plus, other than pub bragging rights. I had a Westfield SE with a stock 1.6 Pinto that was great fun, I moved to a Marlin Roadster fitted with a 3.5 V8 and that was great fun, now I have a Westfield XI with a 1275 A Series and that is great fun. The XI will surprise many normal cars despite its massive 83bhp, the Roadster was extremely quick and made a great noise at circa 180 bhp(plus spat big flames from the side pipes on over run). So go with what you like best, try driving the cars with different engines (or take a passenger ride), don't be put off by the "lesser" HP numbers, bear in mind that the car won't have to haul round huge the weights that a normal car will so needs less power for better performance.
Lazy power delivery from tickover with huge bags of torque off set by potentially weighty cast iron block but simple internals. (SBC/SBF).
Or revvy engine with power made further up the rev range in a potentially lighter but more complex block. (Turbo)
If it's going in a lightweight kit car then IMHO big hp numbers are not necessarily a plus, other than pub bragging rights. I had a Westfield SE with a stock 1.6 Pinto that was great fun, I moved to a Marlin Roadster fitted with a 3.5 V8 and that was great fun, now I have a Westfield XI with a 1275 A Series and that is great fun. The XI will surprise many normal cars despite its massive 83bhp, the Roadster was extremely quick and made a great noise at circa 180 bhp(plus spat big flames from the side pipes on over run). So go with what you like best, try driving the cars with different engines (or take a passenger ride), don't be put off by the "lesser" HP numbers, bear in mind that the car won't have to haul round huge the weights that a normal car will so needs less power for better performance.
The suggen high levels of torque produced by a blown 4 cyl will make a 500kg car a real handful in anything but dry conditions.
Ariel have real problems with the Atom 300 - a good friend of mine consulted with them to try to refine its handling. He was unsuccessful in making any great improvements.
You won't build a 500kg car with an American V8. The whole weight thing with a V8 is a big issue. The car I am building uses the engine and transaxle from an F355 - those two items with all the unnecessary ancilleries (A/C, airboxes, crasppy Ferrari manifolds etc) stripped still weighs in at over 300kgs. Thats an all alloy engine, with titanium rods, slipper pistons etc. An engineering work of art, but not light.
The comemnt that 300bhp 4 cyls don't sound as good as a V8 I would argue. But you need mormal aspiration and a big investment in internals to build a proper race engine. My Seven had effectively a BTTC engine in it 2100cc, 316bhp, 9750rpm. Sounded awesome, but only when being pushed a bit.
The best area to focus is power to weight. Use a big bore bike engine b(1500cc busa etc), knock 100kgs off your target weight and you will have a very quick car whihc also stops and turns far better than most other stuff.
Rememebr 300bhp in a 1000kg car will propell you little faster than 150bhp in a 500kg car.
Ariel have real problems with the Atom 300 - a good friend of mine consulted with them to try to refine its handling. He was unsuccessful in making any great improvements.
You won't build a 500kg car with an American V8. The whole weight thing with a V8 is a big issue. The car I am building uses the engine and transaxle from an F355 - those two items with all the unnecessary ancilleries (A/C, airboxes, crasppy Ferrari manifolds etc) stripped still weighs in at over 300kgs. Thats an all alloy engine, with titanium rods, slipper pistons etc. An engineering work of art, but not light.
The comemnt that 300bhp 4 cyls don't sound as good as a V8 I would argue. But you need mormal aspiration and a big investment in internals to build a proper race engine. My Seven had effectively a BTTC engine in it 2100cc, 316bhp, 9750rpm. Sounded awesome, but only when being pushed a bit.
The best area to focus is power to weight. Use a big bore bike engine b(1500cc busa etc), knock 100kgs off your target weight and you will have a very quick car whihc also stops and turns far better than most other stuff.
Rememebr 300bhp in a 1000kg car will propell you little faster than 150bhp in a 500kg car.
Edited by Fat Arnie on Tuesday 20th April 12:49
Fat Arnie said:
The suggen high levels of torque produced by a blown 4 cyl will make a 500kg car a real handful in anything but dry conditions.
to be fair, 300hp of anything in a 500kg is gonna be a handful in anything other than the dry Edited by Fat Arnie on Tuesday 20th April 12:49
just varying degrees of bottom clenching and eye-shutting required.if turbo'd, a clever enouigh ecu to be able to map the torque curve is essential IMHO. i have 3 maps switchable from the dash in my hillclimber and map 1 is a pussy cat, soft and ideal for the p***ing rain even on slicks, map 2 is more aggressive, ideal for the dry but when im new to a venue in practice, and map 3s the rip-snorter! amazing the differences to drive between the 3, more like 3 differnt engines, in delivery sound and behaviour.
Careful matching of turbo to cam/engine spec, intercooler sizing and intended usage all makes a massive difference. Most seem to bolt some sodding great laggy turbo to a 1.8 engine and expect it to be nice to drive. Well matched specs and most of the turbo delivery horrors are avoided
CNH
LS2 400bhp $5000, reliable and easy...... no contest.....
Supose it all depends on what weight target you have and if there going to be daily drivers or not..... If low weight is what you want and the total weight of the car is closer to 500kgs and longevity isn't as much of an issue then A Turbo Busa setup might be the way...
Supose it all depends on what weight target you have and if there going to be daily drivers or not..... If low weight is what you want and the total weight of the car is closer to 500kgs and longevity isn't as much of an issue then A Turbo Busa setup might be the way...
i would go for an RX7 rotary ............ oh, hang on, i have 
, only trouble is i cant get 300 hp, it wont go that low. At 0.4 bar (wastegate pressure) i have a very linear power curve and 315 fwhp!
An LS engine is a good choice but has nearer 400 hp, they are quite light for their size and when you take away the requirement of oil coolers, intercoolers and the turbo that a 4 pot turbo needs, they are not much heavier. Only problem is the big dollop of torque the v8 gives will easily break traction low down where the right sized turbo 4 pot will give a more gradual climb.
I'm surprised about the comments on the Arial as they use a v tec engine which isnt very toquey and a centrifugal supercharger so you dont get low down torque as the boost builds with the revs so should be a good combination for a light car, clarkson certainly made it look like fun and it set a good time too.
, only trouble is i cant get 300 hp, it wont go that low. At 0.4 bar (wastegate pressure) i have a very linear power curve and 315 fwhp!An LS engine is a good choice but has nearer 400 hp, they are quite light for their size and when you take away the requirement of oil coolers, intercoolers and the turbo that a 4 pot turbo needs, they are not much heavier. Only problem is the big dollop of torque the v8 gives will easily break traction low down where the right sized turbo 4 pot will give a more gradual climb.
I'm surprised about the comments on the Arial as they use a v tec engine which isnt very toquey and a centrifugal supercharger so you dont get low down torque as the boost builds with the revs so should be a good combination for a light car, clarkson certainly made it look like fun and it set a good time too.
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