Good day Gents,


Time for me to move on with my project.
I have a Mazda Rx7 N/A engine which I was planning to fit on my Beach Buggy project.
I think I will finally go for a Subaru engine on that. So!!

I will fit the RX7 engine to my Locost but I only have the engine (without the box).
First of all has anyone fitted a 13B before in a locost?
If so is there a link?

Furthermore, what gearbox shall I use?
RX7 NA / RX7 Turbo

Or can I use from another car:
MAZDA MX5 / BMW / FORD?


The criteria is to:
Fit my Locost by the book chassis
Be able to handle the revs and power from the engine 200bhp
Have a nice usuable ratio


Many thanks in advance,
Alexis

http://www.locostbuilders.co.uk/members/Antnicuk/
Only one I can remember seeing, probably others around though.

http://www.locostbuilders.co.uk/viewthread.php?tid=138346
can this bloke help you
Jacko

Hi
You can use a turbo 11 gearbox, it has lower ratios than the N/A box and a much longer 5th gear. It has a bigger clutch than the N/A. The turbo 11 box is heavier though and you will have trouble sorting a flywheel as the turbo box uses a bigger clutch/flywheel. The N/A box will be cheaper and even with a stock clutch which you could get with it, will take the power you want. The NA box is a very nice box to use, as are all RX7 boxes but if i were you i would probably go for the NA box if you can find one cheap enough, that way you can keep the flywheel you have. The flywheels may just bold on but they have build in counter weight depending on what rotors you have so you cant just bold a turbo f.ywheel to your engine as it will be out of balance, you would need an aftermarket light weight flywheel and a counter weight from an Auto NA engine (rare)

Try RX Motors in Dorset, Tim will help you with what you need.

Fellow member in FDMC ran one in a Se7en type car.
Here's his reply:-
I used a series 3 box from a rx7. I blew that then used a pukka ex works group b rally box. Absolutely fantastic box but you will never find one. The best option is to use the front of a rx7 box which with very little modification gets mated to an mx5 gear casing and then use the rx7 output shaft. It's a good strong box. The mx5 ratios are nice and close(mk1 1600 box from mx5)
If you need engine parts or service please beware. There are some sharks out there and I've learnt the hard way. The only person I would trust is Pip at WGT in Cheshire. He might be a bit dearer than others but you get what you pay for. I've used his engines in the past and his engine in my 7 won me the acsmc sprint championship without missing a beat. He knows his stuff and if/when I go rotary again I will use him

HTH.
Cheers, Pewe10

Hello
Ant too knows his stuff

Hi Brian, fancy meeting you here. Did you use the MX5 box to get the low ratios for sprinting? I cant remember. The NA box raios are a bit long depending on the diff ratio but if its just road driving they should be fine with a 4.1 diff ratio

I destroyed a std box then managed to get my hands on a Group B rally box. It was awesome.
The mx5 adapted box is strong and the ratios are good.

As a side, I missed out on your wide arch kit. That was me the first bidder at £100

Gents, many thanks for all your replies.

First question is whether your suggestions can fit the Locost by the book chassis without modifications
(I am currently using the running gear from an Escort RS2000 SOHC 1980-1982 model incl the 4 speed Gearbox)

A couple of more questions:

1) The Mazda RX7 NA gearbox ratios are much different to the MX5 MK1 ?

2) As per you suggestion: "The best option is to use the front of a rx7 box which with very little modification gets mated to an mx5 gear casing and then use the rx7 output shaft. It's a good strong box. The mx5 ratios are nice and close(mk1 1600 box from mx5)"
Doing some research, some claim that Mazda MK1 1.6 and 1.8 gearboxs have the same ratios, but the internals of the 1.8 are stronger. Is that correct?

3) Are the MX5 gearboxs much different Between MK1-MK2-MK2.5 models? Why not go for a 6 speed?

4) Cant I just use an MX5 gearbox or an RX7 gearbox which will have decent ratios? Dont forget I am running the rear axle from an RS2000 (Any idea what that diff ratio is?)


PS: A friend of mine has a gearbox from a low mileage gearbox from an MX5 MK2 5 speed car. What do you guys think?

The way it looks I think the way forward is to go for an S2000 gearbox to mount my RX7 engine.

The gear ratios are the best I can find from a production gearbox.

S2000 gear ratos:
1st gear - 3.133
2nd gear - 2.045
3rd gear - 1.481
4th gear - 1.161
5th gear - 0.970
6th gear - 0.810

RX8 gear ratios
1st gear - 3.815
2nd gear - 2.260
3rd gear - 1.536
4th gear - 1.177
5th gear - 1.000
6th gear - 0.787

MX5 gear ratios
1st gear - 3.760
2nd gear - 2.269
3rd gear - 1.646
4th gear - 1.257
5th gear - 1.000
6th gear - 0.843


Reading various websites, it seems that this gearbox can fit directly to my FC3s NA engine...
Unless you guys know otherwise.

Any suggestions / comments before I find any nusty/expensive surpises?


PS: Any idea if that gearbox will fit my chassis without any modifications?



[Edited on 10/28/2012 by ALEXARAS]