Design a new sports car engine
Discussion
Hmm,
Not particularly light then, so either capacity or forced induction. Or fancy timing, and stacks of revs.
I would say a combination of both. Has to be fairly compact so V8 (my preference, for the sound) or S6 anything from 3 - 4 litre.
I am a bit old fashioned, so it would be front engine, rwd.
If it is going to include road use, I would go forced induction, for the driveability. Track only then go for the screaming variable timing.
As for power/torque, the sky is the limit with forced induction.
Do you have any designs then?
Sparks
Not particularly light then, so either capacity or forced induction. Or fancy timing, and stacks of revs.
I would say a combination of both. Has to be fairly compact so V8 (my preference, for the sound) or S6 anything from 3 - 4 litre.
I am a bit old fashioned, so it would be front engine, rwd.
If it is going to include road use, I would go forced induction, for the driveability. Track only then go for the screaming variable timing.
As for power/torque, the sky is the limit with forced induction.
Do you have any designs then?
Sparks
some of the people on here already have one (but not me yet). An ultima GTR is your answer IMO. you can build (or get built) to be as radical as you want, from road to full race. as for power plants, chevy SB are the norm (FI and N/A) but the LS1/6s are also starting to show themselves to good effect. also a little lighter than you want at 990kg (according to the lirature). for more info have a look on here or visit the Ultima site www.ultimasportscars.co.uk (i think).
by the way, it is reputed that an Ultima chassis was used by McLarren when designing the F1 as a test bed for suspension and engine!
thanks Chris.
PS. i think this is a graet idea and was only telling you about the Ultima so you guys can get an idea of what they are doing!
by the way, it is reputed that an Ultima chassis was used by McLarren when designing the F1 as a test bed for suspension and engine!
thanks Chris.
PS. i think this is a graet idea and was only telling you about the Ultima so you guys can get an idea of what they are doing!
some of the people on here already have one (but not me yet). An ultima GTR is your answer IMO. you can build (or get built) to be as radical as you want, from road to full race. as for power plants, chevy SB are the norm (FI and N/A) but the LS1/6s are also starting to show themselves to good effect. also a little lighter than you want at 990kg (according to the lirature). for more info have a look on here or visit the Ultima site www.ultimasportscars.co.uk (i think).
by the way, it is reputed that an Ultima chassis was used by McLarren when designing the F1 as a test bed for suspension and engine!
thanks Chris.
PS. i think this is a graet idea and was only telling you about the Ultima so you guys can get an idea of what they are doing!
by the way, it is reputed that an Ultima chassis was used by McLarren when designing the F1 as a test bed for suspension and engine!
thanks Chris.
PS. i think this is a graet idea and was only telling you about the Ultima so you guys can get an idea of what they are doing!
I went around the Ultima factory a few year's ago .. a great experience.
The car is a little too extreme for the road (IMHO) but it's a great car.
I prefer the Noble as a road car after all there are really not many times that 650 bhp is needed when 400 bhp (Max) will do fine.
This was really just a hyprethetical engine build question : i.e. We all currently can just slot in a Rover V8 or SB chevy (LS1/6) but if we wanted to name the ultimate spec of engine what would it be.
I was thinking along the lines of :
V8 (4.5) 60 or 72 degree (not too wide) 4 valve heads
VVC - rev to 7k (max) flat plane crank, dry sump.
About 400 BHP - 380 ft lbs Torque. Weight 220kg.
The car is a little too extreme for the road (IMHO) but it's a great car.
I prefer the Noble as a road car after all there are really not many times that 650 bhp is needed when 400 bhp (Max) will do fine.
This was really just a hyprethetical engine build question : i.e. We all currently can just slot in a Rover V8 or SB chevy (LS1/6) but if we wanted to name the ultimate spec of engine what would it be.
I was thinking along the lines of :
V8 (4.5) 60 or 72 degree (not too wide) 4 valve heads
VVC - rev to 7k (max) flat plane crank, dry sump.
About 400 BHP - 380 ft lbs Torque. Weight 220kg.
Just my two penneth, if it's for road use my ideal would be in the middle and logitudinal (for handling), flat six cylinder (for noise, low c of g and shortness), supercharged (for smoothness of power delivery) ideally with driver variable boost as per the old F1 overtake button and around 2.5 to 3.0 litre capacity. If it were for track maybe go for turbo rather than supercharger or screaming revs from clever timing etc.
I guess I am envisaging the sort of bastard son of a Ferrari 512BB (with the gearbox in-line not under the engine) and an Imprezza. Sound fun?
I guess I am envisaging the sort of bastard son of a Ferrari 512BB (with the gearbox in-line not under the engine) and an Imprezza. Sound fun?
rev-erend said:
OK - on the purely hypethetical world that is PistonHeads :
Let's design a new engine for a 1100kg sports car.
Let's have some idea's for this :
Configuration / target bhp/ torque/ radical or conservative etc..
I've thought the Honda S2000 is a good car with half an engine.
So how about making a full engine?
This of course being a 4.0 V8, 480bhp. Decent output and having lots of revs to play with would make it drivable in tricky conditions (considering the power output).
i like the idea of a V- Vtec if you know what i mean, the NSX was a V6 with the early 90's version of Vtec so how about an I-Vtec flat plane crank V8? around 4litres giving good power circa 500bhp and revving the nuts of itself (im thinking rotary types of rpm!) i guess sort of a japanese designed AJP. could imagine when the cams kick in in would go crazy 
edited!: Duh! just read the post above me and realised its pretty much the same so ill agree with you!
>> Edited by ccharlie6 on Thursday 25th November 18:40
edited!: Duh! just read the post above me and realised its pretty much the same so ill agree with you!
>> Edited by ccharlie6 on Thursday 25th November 18:40
chuntington101 said:
some of the people on here already have one. An ultima GTR is your answer IMO.
by the way, it is reputed that an Ultima chassis was used by McLarren when designing the F1 as a test bed for suspension and engine!
Three yrs ago my answer would have been the same, ie dream car = mid engined V8 500bhp 1000kgs (BTW that GTR weight is dry it'll be around 1080kgs wet).
Thats why I built an Ultima can-am with a 500+bhp SBC and 1010kgs wet... it was almost perfect.
BUT
Now my perfect dream car is mid engined rwd, 600+bhp twin turbo, dry sumped 5-6L V12 (and hopefully under 1200kgs wet).... and I hope to have it finished in 1-2yrs!
The Ultima was just a little to raw to be perfect for me.... saying that if I could financially afford it, It would definatelly still be in my garage. I only sold it to fund my new project
Also it was not only Mclaren that have used the chasis for development... I recently bought new Ultima bits from an abandoned mid engined Aston martin programme... and they had widened the whole chasis by 6inches!
How about a horizontally mounted Radial engine? (not rotary, but a genuine radial like those old WW2 American fighter engines. Say 8 cylinders, 4 litres? Lots of revs, no vibes.
OK, so the exhuast manifold design might be a challenge, but the noise would be awesome and it could be mounted nice and low in the chassis.
Andy
OK, so the exhuast manifold design might be a challenge, but the noise would be awesome and it could be mounted nice and low in the chassis.
Andy
I'm fed up of dead end car design. It's the understandable result of optimisation/powerplant sharing. But then how far do you go before being different is just being silly. Trying to strive for something artistic but that still satisfies functional criteria. The engine of choice for me would have to be naturally aspirated, for pure NVH reasons.
I also don't like the sound Flat plane crank V8s make.
I would most likely do a 2.8 litre cruciform crank V8.
To reduce the thermal inefficiencies of such small cylinders I would have the engine be capable of running as a equal-phase-(cross bank)-firing 4 cylinder. Running as a 1.4 litre 4 cylinder should allow the car to run through various cruise cycles and still achieve reasonable fuel economy ( perhaps some vehicle simulation work would be required to finalise the capacity).
The second departure from modern thinking would be- that it would have a single central cam shaft- but mounted reasonably high up in the block a la 1960s Daimler/SP250 V8. The valves would be actuated by short pushrods-which are more akin to "thick rocker beams". However before this- each one would have a hydraulic collapsable tappet. This would facilitate the cylinder deactivation for fuel economy/part load operation.[Deactivating valves for the inactive cylinders reduces pumping losses further]. The single cam in the cooler cylinder block- should allow a more favourable regime of lubrication- with potentially good oil supply for lower friction (check out a Stribeck curve for regimes of lubrication). This is in addition to the fact that there is only one camshaft- which lowers the numbers of bearings and lobes etc etc.
Use a variable cam timing phasor- that shifts both intake and exhuast cam profiles equally- again good for part load fuel economy- the late IVC combined with late EVO help here.
The engine would be a 2 valve hemi configuration- with a system of rockers actuating the exhaust valves.
Cynics might say that the valve train inertia would be high- thus limiting valve accelerations, but I would go some way to compensating by using curved rocker pads at the cam lobe/lifter interface and a decent rocker arm ratio (say 1.55:1)- which will allow as much lift as possible for a given duration.
Twin plugs per cylinder will get the burn rates up and shorten long flame paths often endemic with a 2 valve layout. This combined with the small bore should allow a highish compression ratio of 11.5 or may be even 12:1
I'd route for an 81mm bore with an nice 68 mm stroke. I'd use bore centres of about 88mm so there is some opportunity to enlargen the engine with evolution. Alloy block, with alloy head, either hypereutectic block or liners but NOT open deck design- if this engine were to be boosted some day, the block would need rigidity!
Forged steel nitrided crankshaft- allows the use of small diameter bearings. Engine structure sized for a rev limit of about 7350 rpm.
The 2 valve lay out will mean a richer rortier exhaust note. Aim for a shallowish chamber valve angle of about 22 degrees, and a 43mm diameter intake valve. Although only a two valve the combined valve total area and curtain area of all the valves would be higher then that of a Honda S2000-with a MUCH nicer noise.
Intake manifold design would have as straight a run as possible into the head, individual port thorttles would be used to give lightening throttle response- while giving a smoother idle AND better part load fuel economy (quicker pressure recovery during the 'pumping loop'). Would aim for a front feed plenum design for a rorty/burbly 'uneven' noise- probably dominant in 3.5th, 4th 4.5th and 8th order harmonics in terms of NVH sound quality.
I think targets for peak power are 240 Bhp-85 Bhp/litre at about 6850 rpm. This is very good figure for a two valve engine. Expect about 11.9 bar BMEP (again a VERY good figure for a 2 valve engine)- which is about 196 lb ft- at 5200 rpm.
A realistic target weight - due to lack of all the usual modern assoiated componentry is about 145-150 Kgs.
In this vehicle it would give good fuel economy, great reliability from simplicity, GREAT sound, good refinement (for a sporty engine)and be charismatic and quirky. It would be "fast enough" and not stupidly/obscenly fast like my 993 TT, so expect a 0-60 mph in under 5.5 seconds.
I also don't like the sound Flat plane crank V8s make.
I would most likely do a 2.8 litre cruciform crank V8.
To reduce the thermal inefficiencies of such small cylinders I would have the engine be capable of running as a equal-phase-(cross bank)-firing 4 cylinder. Running as a 1.4 litre 4 cylinder should allow the car to run through various cruise cycles and still achieve reasonable fuel economy ( perhaps some vehicle simulation work would be required to finalise the capacity).
The second departure from modern thinking would be- that it would have a single central cam shaft- but mounted reasonably high up in the block a la 1960s Daimler/SP250 V8. The valves would be actuated by short pushrods-which are more akin to "thick rocker beams". However before this- each one would have a hydraulic collapsable tappet. This would facilitate the cylinder deactivation for fuel economy/part load operation.[Deactivating valves for the inactive cylinders reduces pumping losses further]. The single cam in the cooler cylinder block- should allow a more favourable regime of lubrication- with potentially good oil supply for lower friction (check out a Stribeck curve for regimes of lubrication). This is in addition to the fact that there is only one camshaft- which lowers the numbers of bearings and lobes etc etc.
Use a variable cam timing phasor- that shifts both intake and exhuast cam profiles equally- again good for part load fuel economy- the late IVC combined with late EVO help here.
The engine would be a 2 valve hemi configuration- with a system of rockers actuating the exhaust valves.
Cynics might say that the valve train inertia would be high- thus limiting valve accelerations, but I would go some way to compensating by using curved rocker pads at the cam lobe/lifter interface and a decent rocker arm ratio (say 1.55:1)- which will allow as much lift as possible for a given duration.
Twin plugs per cylinder will get the burn rates up and shorten long flame paths often endemic with a 2 valve layout. This combined with the small bore should allow a highish compression ratio of 11.5 or may be even 12:1
I'd route for an 81mm bore with an nice 68 mm stroke. I'd use bore centres of about 88mm so there is some opportunity to enlargen the engine with evolution. Alloy block, with alloy head, either hypereutectic block or liners but NOT open deck design- if this engine were to be boosted some day, the block would need rigidity!
Forged steel nitrided crankshaft- allows the use of small diameter bearings. Engine structure sized for a rev limit of about 7350 rpm.
The 2 valve lay out will mean a richer rortier exhaust note. Aim for a shallowish chamber valve angle of about 22 degrees, and a 43mm diameter intake valve. Although only a two valve the combined valve total area and curtain area of all the valves would be higher then that of a Honda S2000-with a MUCH nicer noise.
Intake manifold design would have as straight a run as possible into the head, individual port thorttles would be used to give lightening throttle response- while giving a smoother idle AND better part load fuel economy (quicker pressure recovery during the 'pumping loop'). Would aim for a front feed plenum design for a rorty/burbly 'uneven' noise- probably dominant in 3.5th, 4th 4.5th and 8th order harmonics in terms of NVH sound quality.
I think targets for peak power are 240 Bhp-85 Bhp/litre at about 6850 rpm. This is very good figure for a two valve engine. Expect about 11.9 bar BMEP (again a VERY good figure for a 2 valve engine)- which is about 196 lb ft- at 5200 rpm.
A realistic target weight - due to lack of all the usual modern assoiated componentry is about 145-150 Kgs.
In this vehicle it would give good fuel economy, great reliability from simplicity, GREAT sound, good refinement (for a sporty engine)and be charismatic and quirky. It would be "fast enough" and not stupidly/obscenly fast like my 993 TT, so expect a 0-60 mph in under 5.5 seconds.
Marquis_Rex said:
It would be "fast enough" and not stupidly/obscenly fast like my 993 TT, so expect a 0-60 mph in under 5.5 seconds.
I have a GT3 box which I beleive is the same as the 993TT box (and GT2)... been trying to source a starter for it but they are horifically expensive (4x the price of a G50 unit) to the point that I am going to design a whole new ringear and put the starter on the engine side.
on the engine side, if you want a reliable 400bhp then why not look at the LS1/6? out of the vette you will get that as standerd and with a little work yopu could get it to rev to 7 no problems. also there is a world of tuning stuff out there for them (and it getting bigger), there are loads of them about, they will be in production for a while yet, they will fit into anything a SBC will fit (size vise, i think) and they sound sooooo nice. IMO
all you need now is to get some 4valve per cyclinder heads cast up and you would be well away! hehe
alternativly look at the ford V8s. alreday ahve the above, but are a little smaller
thanks Chris.
all you need now is to get some 4valve per cyclinder heads cast up and you would be well away! hehe
alternativly look at the ford V8s. alreday ahve the above, but are a little smaller
thanks Chris.
I have an issue with all the "big V8" comments. Given current crash- and pedestrian-protection legislation around, lots of mundane cars are hitting 1,100kg, e.g.
- New fiesta with a 1.4 or 1.6 petrol
- Clio 182
neither of which could even think of containing a V8.
So...unless our car is going to be fibreglass bodied we need something arguably smaller than a Boxster (> 1,200kg),so we've 2 routes:-
1) SVA to avoid crash-regs, then anything's game, but that's just going to be a track-toy, not a practical car.
2) Small-hatch / small-coupe / roadster with moderate capacity I-4, I-5 or I-6.
So we've got an engine of < 3-litre capacity, probably no more than 2.5. Ally block. DOHC.
So choices:-
- Forced Induction (turbo - cheaper and lighter than supercharger)
- Variable cam and valve, a-la BMW/Honda.
My proposal: How about an iVTEC inline 5 or inline 6??? Polished ports, oval-profile titanium springs... (i.e. all the tech from the hand-built Integra engine)
Sufficiently balanced, it'll rev to 9k, kick out ~300bhp in 2.5litre form. In an 1,100kg car you've got GT-3 levels of bhp/tonne, enough to see off almost anything on the road. Revving the engine is fine as it's for enthusiasts, and normally-aspirated keeps the cooling requirements down, and hence the engine weight. Also lower torque means lighter 'box and clutch, so we're now in the virtuous circle of weight...
In concept, I see it as somewhere between an S2000 and a lightened 350Z.
- New fiesta with a 1.4 or 1.6 petrol
- Clio 182
neither of which could even think of containing a V8.
So...unless our car is going to be fibreglass bodied we need something arguably smaller than a Boxster (> 1,200kg),so we've 2 routes:-
1) SVA to avoid crash-regs, then anything's game, but that's just going to be a track-toy, not a practical car.
2) Small-hatch / small-coupe / roadster with moderate capacity I-4, I-5 or I-6.
So we've got an engine of < 3-litre capacity, probably no more than 2.5. Ally block. DOHC.
So choices:-
- Forced Induction (turbo - cheaper and lighter than supercharger)
- Variable cam and valve, a-la BMW/Honda.
My proposal: How about an iVTEC inline 5 or inline 6??? Polished ports, oval-profile titanium springs... (i.e. all the tech from the hand-built Integra engine)
Sufficiently balanced, it'll rev to 9k, kick out ~300bhp in 2.5litre form. In an 1,100kg car you've got GT-3 levels of bhp/tonne, enough to see off almost anything on the road. Revving the engine is fine as it's for enthusiasts, and normally-aspirated keeps the cooling requirements down, and hence the engine weight. Also lower torque means lighter 'box and clutch, so we're now in the virtuous circle of weight...
In concept, I see it as somewhere between an S2000 and a lightened 350Z.
ok then so not a V8 engine how about a 2 litre inline four but using rotary valve technology? this due to the combustion chamber size and the fact that the valves dont protrude into the chamber could be made to run a very high compression ratio and also higher revs due to valvetrain (not the axial seals though). it should produce a good amount of power, unfortunately there aren't too many ratary valved engines around to compare with, its something different though.
andymadmak said:
How about a horizontally mounted Radial engine? (not rotary, but a genuine radial like those old WW2 American fighter engines. Say 8 cylinders, 4 litres? Lots of revs, no vibes.
OK, so the exhuast manifold design might be a challenge, but the noise would be awesome and it could be mounted nice and low in the chassis.
Andy
One of these ..
www.russianaeros.com/vedenyevproduct.htm
And exactly where in the car would you mount this??? By my calculations, this would have to be at least 20-30% wider than a Scooby flat-four, which already challenges the engine bay of the scoob, once plumbed in.
Remember we're building a lightweight sports car!?!
Lovely idea though...if a little impractical. On a serious note, I think the engineering compromises on these made in-line and V engines far superior in aircraft (drag may have had a little part to play, too!), as the last radial-engine aircraft were designed (in the West) immediately post-WW2, using WW2 engines and tech...
Remember we're building a lightweight sports car!?!
Lovely idea though...if a little impractical. On a serious note, I think the engineering compromises on these made in-line and V engines far superior in aircraft (drag may have had a little part to play, too!), as the last radial-engine aircraft were designed (in the West) immediately post-WW2, using WW2 engines and tech...
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