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  #11  
Old 25th March 2011, 04:35 PM
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Airhead Airhead is offline
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It is perfectly feasable to cut the steel for the chassis yourself, the old adage "measure twice cut once" was written by someone building a Locost.

Personally I used an Escort rack as it fits the front frame perfectly avoiding issues with bump-steer, the Mazda unit is too wide so needs a section cut out of the actual cylinder which is just too big a risk IMHO.

I was originally going to use the MX5 pedal box but am having second thoughts due to the available space so will most likely go with the book offering.

The other main things I can think of are that you can't get off the donor are the shocks.

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  #12  
Old 25th March 2011, 04:41 PM
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Ahh thanks Airhead, think I'll buy enough steel to make the bottom frame and see how I get on. If I fail I'll buy precut stuff, money, or the lack of it is my main motivation!
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  #13  
Old 25th March 2011, 08:35 PM
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I've had a 1.8 for a couple of years now, and just bought a 1.6 for my donor.
There's not a lot in it, but the 1.8 does feel a tad quicker.
Either should be a whole lot of fun in the roadster though
If you do go 1.6 I'd avoid the early shortnose crank engine (up to about 1991).
The 1.8 diffs might be heavier, but they're also a lot tougher. The 1.6 diffs are a bit weak and break if abused - particularly if turbo'd.
You can retrofit the 1.8 diff onto the 1.6, but they go for silly money, and you have to change the driveshafts and propshaft whilst you're at it.
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  #14  
Old 26th March 2011, 04:26 PM
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Quote:
Originally Posted by skov View Post
If you do go 1.6 I'd avoid the early shortnose crank engine (up to about 1991).
Thanks for your input. What's the issue with the shortnose type is it the crank pulley damaging the keyway as I have an good easy fix for that sort of thing I've done in the past. Good info about the diff does this still apply to a 1.6 v-spec lsd?
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  #15  
Old 26th March 2011, 11:05 PM
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Quote:
Originally Posted by CTWV50 View Post
Thanks for your input. What's the issue with the shortnose type is it the crank pulley damaging the keyway as I have an good easy fix for that sort of thing I've done in the past. Good info about the diff does this still apply to a 1.6 v-spec lsd?
I think there's a couple of failure modes - the keyway getting damaged, and the threads in the end of crankshaft failing. The usual fix is an engine swap!

I'm pretty sure the 1.6 LSDs were all viscous, and the 1.8 LSDs were torsen.
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  #16  
Old 27th March 2011, 10:23 PM
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In terms of bhp difference between the 1.6 and 1.8 this is what I have found during my research (hopefully correct)

UK Cars Only
Mk1 1.6 - 89 to 94 = 114bhp.
Mk1 1.6 - 95 to 98 = 88bhp.
Mk2 1.6 - 98 on = 108bhp.

Imports
Japan never used the 88bhp engine so all imported Mk1 1.6 are 114bhp.

HTML Code:
Year         Model   Chassis   Engine code    Transmission     Power
1989–1993    1.6i    NA        B6ZE(RS)       5-speed MT       114 bhp
1995–1998    1.6i    NA        BP-4W          5-speed MT       88 bhp
1998–2001    1.6i    NB        BP-4W          5-speed MT       108 bhp
     
1993–1995    1.8i    NA        BP-4W          6-speed MT       128 bhp
1995–1998    1.8i    NA        BP-4W          6-speed MT       133 bhp
1998–2001    1.8i    NB        BP-4W          6-speed MT       140 bhp
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  #17  
Old 28th March 2011, 12:19 AM
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I thought the 88bhp engine was from 1996 on or at least sept 1995. I've just bought a may-95 car!! I do hope you're wrong!

From Wiki

The new 1.8 L (110 cu in) engine produced 98 kW (131 bhp), which was then increased to 99 kW (133 bhp) for the 1996 model year. The base weight increased to 990 kg (2,200 lb). Performance was improved slightly, the additional power being partly offset by the extra weight. In some markets such as Europe, the 1.6 L (98 cu in) engine continued to be available as a lower-cost option, but was detuned to 66 kW (89 bhp). This lower-powered model did not receive all the additional chassis bracing of the new 1.8 L (110 cu in). Japanese and US cars were fitted with an optional Torsen LSD, which was far more durable than the previous viscous differential.
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  #18  
Old 28th March 2011, 12:50 AM
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Just found this.......

Taken from the Mazda Workshop manual (12/94)

Engine
The purpose of the modification is to increase the low speed torque by changing the valve timing and compression ratio.
The following parts have been modified

The configuration of the camshafts have been modified
Valve timing
IVO 5* BTDC
IVC 40* ABDC
EVO 55* BBDC
EVC 5* ATDC

The configuration of the pistons have been modified
Compression Ratio - 9.0:1

Fuel & Emission Control System
According to the readoptaion of the B6 engine model, the following changes have been made.

Injection method has been changed from the two-group injection to the sequential injection.
IAC load correction has been added according to the addition of the rear window defroster signal input to the ECM.
IGF signal input to the ECM has been discontinued.
Signal names have been changed as follows. NE = SGT & G = SGC
Diagnostic trouble codes No. 01 have been discontinued.
Vehicle speed sensor input have been added.
In the exhaust system, the front pipe and the parts after it are the same as that of the BP engine model.
The heated oxygen sensor has been adopted and its instulation position has been changed.
The fuel tank capacity has been enlarged and the cruising range has been increased accordingly.
Features - Excellent drivability and improved engine performance due to Squential mulitport fuel injection


Have asked seller of car to email me the VIN number

The car will not be an import. It will be a UK registered car from between 1995-1997.


VIN number will be JMZNA18C200 something, something, something, something, something, something.

(The letter C tells you it's a low power 1600, B for high power 1600, P for 1800 or 6 for NB 1600)
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  #19  
Old 28th March 2011, 10:00 AM
Blacktop Blacktop is offline
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Quote:
I thought the 88bhp engine was from 1996 on or at least sept 1995. I've just bought a may-95 car!! I do hope you're wrong!

From Wiki

The new 1.8 L (110 cu in) engine produced 98 kW (131 bhp), which was then increased to 99 kW (133 bhp) for the 1996 model year. The base weight increased to 990 kg (2,200 lb). Performance was improved slightly, the additional power being partly offset by the extra weight. In some markets such as Europe, the 1.6 L (98 cu in) engine continued to be available as a lower-cost option, but was detuned to 66 kW (89 bhp). This lower-powered model did not receive all the additional chassis bracing of the new 1.8 L (110 cu in). Japanese and US cars were fitted with an optional Torsen LSD, which was far more durable than the previous viscous differential.
The table above was taken from the Technical Specifications section from Wiki so looks like there is conflicting info on the same Wiki page
http://en.wikipedia.org/wiki/Mazda_MX-5
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  #20  
Old 28th March 2011, 11:21 PM
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Actually I think I've bought the 90bhp version but on inspection is a good base for my build, local, has 9:1 CR, and overall looks a straight deal. Picking it up tomorrow.
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