How much difference does 2" make? (Choosing engine mounting location...)

[Stefan]

I've reached the point where I need to decided whether to:

* Mount 1G such that gearbox is 2" back from stock

1. Better weight distribution
2. Already have plug & play Kaizen engine mounts & gearbox mounts to suit this position
3. Have to massage firewall in middle where heater box is, and heater box location is flush with firewall, so have to relocate heater box and/or core slightly, and modify heater core firewall piping location :S
4. Have to shorten tailshaft (no big deal)

* Mount 1G such that gearbox is in stock location

1. A lot easier, but worse weight distribution. Nearly everyone does it this way
2. Have to mod sump to clear swaybar (no big deal)
3. Mod custom mounts slightly (no big deal)

So my question is - is sitting the engine back 2" worth it? Would be weight distribution make a noticeable difference from the driver's seat? Any input appreciated.

[abently]

Short answer is No

Spend your money on getting custom rate shocks and springs suited to your front/ rear weight distribution.

[roadsailing]

what car is it?

if i could move my engine back 2 inches fairly easily i would think about it, as much to get the gearstick back a bit as anything. if your car has a heavy front bias i'd consider it, but do some calcs and work out what % difference it makes.

[Stefan]

Just clicky my sig to see what car I have

[roadsailing]

oh sorry

just stick it in as per factory, if it bothers you change it, but im sure it wont that much, just move stuff into the back and dont worry about it too much.

actually, here is a question, do you notice much of a handling difference with a full or empty fuel tank? thats probably a similar ballpark effect on weight distribution than moving the engine back 2 inches

[Stefan]

Thanks for that. Yes I do notice (though I haven't had a full tank in years, I usually only ever half fill it). Would have thought ~30 kgs behind the the rear axle line would make more difference that a small slice of engine... then again, maybe not.

No idea how to calculate btw.

[Talasas]

I don't think it would make a grand difference, 5" or more might become more noticable, but not 2". From memory to calc the C of G you need the individual weights at each wheel and then measure their distance from a datum point (don't know how this is established), maybe the centre of the car.

["Z" UTE]

My objective when fitting "other" engines to Celica's and Crowns, is best weight distribution. To achieve this without firewall mods, I use 10-12mm wooden spacer blocks, under the engine, and between the engine and firewall. This locates the engine in position ready for engine mount fabrication, sump mods, and gearbox crossmember fabrication.
Naturally a good suspension setup is going to help, but will not change the vehicles centre of gravity.

Cheers Chuck.

[love ke70]

50mm, its a fair bit.
do it
i know a guy called time with a ga65, his motor sits heaps back and his car drifts very well, so it does make a difference.

i have no specific details on how far back the motor is, sorry.

[Stefan]

Lol, I have Tim's old 1G setup and the same Kaizen mounts that sit the engine 2" further back and necessitate firewall mods.

[Cuts]

datum point in aircraft is based apon the c of g (centre of gravity). so find that with motor in stock position, then calculate again with motor 2" further back.

or prehaps having a knowledge of the front/rear weight distribution from the factory, then setting it up 2" further back and go again, see if its closer to 50/50.

[love ke70]

hed bashed the crap out of his firewall hadnt he? was that with the kaizen mounts? or did they take it a further 2 inches?

[Stefan]

hed bashed the crap out of his firewall hadnt he? was that with the kaizen mounts? or did they take it a further 2 inches?

The Kaizen mounts sit the engine and gearbox 2" further back from the gearbox's stock location, which requires some massaging of the firewall in the middle.

[Stefan]

My objective when fitting "other" engines to Celica's and Crowns, is best weight distribution. To achieve this without firewall mods, I use 10-12mm wooden spacer blocks, under the engine, and between the engine and firewall. This locates the engine in position ready for engine mount fabrication, sump mods, and gearbox crossmember fabrication.
Naturally a good suspension setup is going to help, but will not change the vehicles centre of gravity.

Cheers Chuck.

Good idea. Sounds like you often shorten the tailshaft a tad.

P.S. Those coilovers went to good use

[Stefan]

Thanks to everyone for their replies. The RA65 is 52/48 from the factory, IIRC. Calculating anything more, eithout knowing exact weights of each engine, is a bit beyond me.

I've decided to NOT touch the firewall at all, as the other option is too much effort and a bit iffy. The engine will still be mounted as far back and as low as possible.