V6, Inline 6 or Inline 5??

[KFC]

I don't have the chassis yet as I might need to make changes to the chassis before it's built.

I'm trying to decide on what engine to fit to the "haynes" chassis.

V6? BMW 2.5L or 3.0L or the Fiat coupe inline 5 20v engine?

Obviously it would be much easier to fit the MX5 running gear, engine and gearbox. I just thought if I'm going to build it then do it with style, twin exhaust with that lovely sound of a V6.

I thought the duratec V6 would fit better than a M52 BMW engine, both with standard gearboxes fitted to their engines but the Duratec seems quite heavy, 200kg? Upset the handling too much?

Any thoughts on the complications of mix matching gearboxes and rear gearbox with diff out of 2000 Audi A6 to try and balance the car better or is it just not worth the agro?

Thanks in advance

Kev

[Davey]

"In my humble opinion, big heavy blocks arent ideally suited to a lightweight sportscar, generally youll see a lot of understeer and a bit too much torque at the back. Thats just my opinion though so dont take it too seriously."

A heavy motor isn't ideal for a lightweight sports car I agree but it doesn't necessarily upset the handling and doesn't necessarily give understeer. If it is mounted further back in the engine bay to centralise its mass then it shouldn't give any more understeer than a Zetec would.

"too much torque at the back" I don't understand what you're saying here. Do you mean it would give too much torque at the wheels being a bigger engine with more torque produced lower in the rev range or are you suggesting the torque reaction might twist the chassis?

Having been in the motor and related industries for 35 years I was brought up on the principle of TTW, Torque Turns Wheels. Personally I'd rather have a bigger motor giving a wide spread of torque across the range over a small capacity revvy lump with little torque at the bottom end and then a sudden surge higher up the rev range. Each to their own of course but with a better spread of torque you don't always need to be changing gear to keep it in the "power band".

It also depends on what you intend to do with the car, if its intended as a quick and fun roadcar, as mine is planned to be, then the bigger lump will give more relaxed driving. If you intend to use it mostly at track days or even as a full on race car, whether for hillclimbing/sprinting or circuit racing then the smaller capacity, lighter weight peaky engine may well be a better option.

Just my thoughts,
D.

[robo]

There is no "better" engine, I can understand someone building a 1ltr roadster the same as I do a 3ltr. I prefer the bigger lazy unfussed lumps but thats just me. Its no different than a bike really, you see kids laying flat on their tanks with bikes at 40mph screaming the nuts out of them, big bike comes past at little over tickover at the same speed [no noise]. Same job different approach both riders are happy.
The engine weight thing is a non issue within reason as some of the four pot engines are as heavy as the sixes and eights, the difference is less than a good dump after a curry night..

1.3 13B TT (FD) Alone
+ Five Speed

CA18DET with trans 389lb

SR20DET Complete
+ Five Speed 490lbs (source Sport Compact Car)

Datsun L6 Alone
+ Four Speed

toyota 1UZ-FE + R154 mission 486lbs
+ W58 mission 466lbs

RB25DET Alone
+ Five Speed 700 lb complete

RB26DETT Alone
+ Six Speed

L28 complete with stock manifolds, SU's, and A/C compressor + 5 spd 523lbs

7MGTE complete with turbo and A/C compressor 515 lb
w/ R154(125lbs alone) 640lb

2JZ-GTE Alone 594 lbs
+ Getrag Six Speed 746lbs

VH45 508 lbs

LS1 Alone
+ T56 Six Speed

Chevy L98 Alone 540 lbs with iron heads, 510 lbs with aluminum heads
+ 4+3 OD

Chevy LS1
459(automatic)
503(manual)

LT1/LT4
562 (automatic)
620 (manual)

LT1/LT4 Alone
562 (automatic)
620 (manual) ZF Six Speed

Chevy SB (All Iron) Alone 575 lbs
+ T56 Six Speed

Chevy SB (iron + Aluminum) 500 lbs
+ T56 Six Speed

Ford SB (All Iron) Alone 550 lbs ?
+ T56 Six Speed

Ford SB (iron + Aluminum) Alone 470 lbs?
+ T56 Six Speed

Chevy BB (All Iron) 685 lbs
+ T56 Six Speed

Chevy BB (iron + Aluminum) Alone 590 lbs
+ T56 Six Speed

Viper 8.0 L alone 716 lbs
+ T56 Six Speed

Viper 8.2 L alone 716 lbs?
+ T56 Six Speed

Bob

Guilty of going V8

[wylliezx9r]

My argument is, that these cars need very little torque. My car will trundle around @ 30 mph in 6 th gear easy, I proved it to a guy at a show the other week and he couldn't believe it. And will do 60 in under 5 secs and has enough power for power over steer when it takes your fancy.
I guess as others have said though, ultimately its what you wnt from the car, tourer, track car, mix of the both. But in my opinion lighter must be better

[robo]

http://westfield-world.com/power-to-weight.html

Have a fiddle with the above, just love power The weight difference of a light four pot to a medium weight 6 pot is about 5% on a total build which is more than enough for the bigger engine to cope with.

Bob

[shh120m]

Originally Posted by Davey

"In my humble opinion, big heavy blocks arent ideally suited to a lightweight sportscar, generally youll see a lot of understeer and a bit too much torque at the back. Thats just my opinion though so dont take it too seriously."

A heavy motor isn't ideal for a lightweight sports car I agree but it doesn't necessarily upset the handling and doesn't necessarily give understeer. If it is mounted further back in the engine bay to centralise its mass then it shouldn't give any more understeer than a Zetec would.

"too much torque at the back" I don't understand what you're saying here. Do you mean it would give too much torque at the wheels being a bigger engine with more torque produced lower in the rev range or are you suggesting the torque reaction might twist the chassis?

Having been in the motor and related industries for 35 years I was brought up on the principle of TTW, Torque Turns Wheels. Personally I'd rather have a bigger motor giving a wide spread of torque across the range over a small capacity revvy lump with little torque at the bottom end and then a sudden surge higher up the rev range. Each to their own of course but with a better spread of torque you don't always need to be changing gear to keep it in the "power band".

It also depends on what you intend to do with the car, if its intended as a quick and fun roadcar, as mine is planned to be, then the bigger lump will give more relaxed driving. If you intend to use it mostly at track days or even as a full on race car, whether for hillclimbing/sprinting or circuit racing then the smaller capacity, lighter weight peaky engine may well be a better option.

Just my thoughts,
D.

Im not too sure i would want to point your car into a corner, it looks rather heavy, and the chassis steel looks rather "pitted", especially the rails where the rear shock mount is fitted. I think your misguided on your torque principle, however you may need alot to move your barge of a car

Just my opinion


Nathan

[robo]

Not all the cars are being built to race round coke cans in a car park

Bob

[michael92]

I dont think there will be any problems I have a vauxhall v6 and omega box, and ive mounted mine as far back as possible! the only downside is.... I have to buy 2 cat converters expensive!!

[Davey]

Originally Posted by shh120m

Im not too sure i would want to point your car into a corner, it looks rather heavy, and the chassis steel looks rather "pitted", especially the rails where the rear shock mount is fitted. I think your misguided on your torque principle, however you may need alot to move your barge of a car

Just my opinion


Nathan

Can you not express your opinion without resorting to insulting words? BARGE? Really?
Yes it is going to be heavier than many other Haynes builds but as I said I'm building it for a quick road car not a circuit racer or hillclimber/sprinter. Having said it will be heavier it will still only be 750KGs ish, with C225BHP and a likely torque output of 200 ft/lbs plus it will still outpace most hot hatches and with pretty equally balanced weight distribution fornt to rear it should handle OK!

The steel may look pitted but as it is 3.2mm wall thickness there is no serious loss of strength, in fact it will almost certainly have more torsional rigidity than the standard book spec car.

I'm mistaken am I? TTW pal, TTW!

D.

[robo]

If yours is a barge mine must be the Titanic TTW is bang on , as the yanks say "there aint no replacement for displacement"

Bob