The mx5 Rv8,.. thing!

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JP.
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Post by JP. »

Think its time to do some measuring.................
Got this hint on this forum and have three Capri's running with it now....
Take a look my friend http://www.dynotunenitrous.com/store/sc ... roduct=149


'73 Ford Capri. 3.5 RV8, Magnacharger 110 Supercharger, Merlin F85 Heads, Water/Methanol Injected
'73 Ford F250, 6.7ltr V8
Building a GT40 mk2

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topcatcustom
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Post by topcatcustom »

Hi JP, I already have one like this http://www.aemelectronics.com/wideband- ... -gauge-25/

Just going to play with the timing and carb over the weekend. What timing do you use and how many miles/kilometres per gallon/litre do you get?
TC

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topcatcustom
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Post by topcatcustom »

Didn't get much time on the car itself over the weekend as had a massive tidy up and was generally busy, though took it out for a spin again today after boxing in my rad with 1mm ally sheet, also put some richer rods in the carb and runs a pretty steady 12.5:1(ish) AFR. I also cranked the static timing to 20btdc and once run for 30seconds she will happily idle and revvs even free-er than before but I do need to back off the total advance when running under boost as it's poppin a bit under load, hopefully a bit of retard will sort that, which I will try and set up by using the vacuum advance once I slightly modify it so it fits under my top hose.

She ran about 5 degrees cooler today which I'm not sure is down to the richer mix and enclosing the radiator, or just because it's about 10 degrees cooler than last weekend when I drove it!

I'm going to get myself a gunson colortune as a second opinion from my afr gauge, it should tell me if anything is out as it is damned thirsty. Oh- also still getting dropping fuel pressure but I took the pump base and pressure relief valve apart and was basically as new, I also took the cap and diaphram off the regulator- as new and couldn't find anything to go wrong- they are both so simple I'm lost as to how anything can vary with them :?:
TC

bigaldart
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Post by bigaldart »

Tom,

To limit total advance have a look at the way the weights swing and there will be a stop to limit maximum advance. You can then either build up the weight, which will bring timing in faster, but do it so that the weight hits the stop sooner, otherwise if its a pin type stop you can bush the pin to limit travel. Another alternative is to find a distributor shop tell them how much mechanical advance you want and they can recurve it to suit. It doesn't cost a lot and you will know exactly how much you have and at what rpm you have max advance. Rovers generally have a very slow curve and are a lot happier with a faster one. Ideally you want all advance in at about 3000 rpm.

Alan

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topcatcustom
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Post by topcatcustom »

Cheers Al, I now have a set of springs (thanks MuscleManta) for the dissy and will pop a bush over the pin to limit the advance to about 10degs or so, I can make up a few small bushes on the lathe so should be easy to mess around with.
TC

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topcatcustom
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Post by topcatcustom »

Well- after playing with the dissy and a few other bits, she pulls like a train with no missfire :D :D :D (until you stop accelerating and it pop pop pops back down). It does smoke a bit when you put your foot down apparently but I'm putting that down to too large ring gaps, which was my doing. I'd still rather that than risk them butt under boost though...

No heat problem though it I would still like it to run 5-10 degs cooler, I have boxed in the rad fairly well, not completely air tight as the inside of the bumper is a complex shape, it has a 75deg 'stat fitted with 2no. 4mm holes drilled in the top. The rad is all ally and 2" thick so cannot get any bigger or better in there. Apart from trying some wetter water what else can I do to shave a few more degrees off the running temp?
TC

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topcatcustom
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Post by topcatcustom »

As posted in the dyno section- she made 368bhp on the rollers today at 7000rpm, 330 at the wheels, and 278ftlb torque. No curve whatsoever just pulled and pulled until he let the throttle go! VERY happy with that :D
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Post by bigaldart »

Superb Tom,

Got to be happy with those figures. The torque curve is just typical for a blower, will go on and on until it breaks. Well done mate.

Alan

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topcatcustom
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Post by topcatcustom »

Got a couple of vids from the rollers-



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JP.
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Post by JP. »

Allready thought it to see in your sheet but after watching the vid..........is your measurement taken in thirth gear ???????? and not in fourth (price direct).

Its a pitty you don't have a torque sheet, I was realy curious about the caracteristics of the blower cam.
'73 Ford Capri. 3.5 RV8, Magnacharger 110 Supercharger, Merlin F85 Heads, Water/Methanol Injected
'73 Ford F250, 6.7ltr V8
Building a GT40 mk2

mgbv8
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Post by mgbv8 »

Look cool Tom!

Was the car not strapped down on the dyno?

Perry Stephenson

MGB GT + Rover V8

9.62 @ 137.37mph

Now looking for 8 seconds with a SBC engine

http://www.youtube.com/watch?v=nVscbPHgue0&list=UUqIlXfSAoiZ--GyG4tfRrjw



https://www.youtube.com/watch?v=eg3avnsNKrc&index=2&list=FLqIlXfSAoiZ--GyG4tfRrjw

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topcatcustom
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Post by topcatcustom »

It was in 4th gear JP, I may plot the torque onto a graph as it does slow down quite quickly after about 6krpm.

Pel yes it was- had a long strap on the rear and the front was chocked! He wasn't expecting as much power as it made- neither was I!
TC

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Post by mx5v8 »

Great vids, that sound is awesome. Love to see this car. Thought about going to Retro show but not to sure if my car will be back on the road as I've just snapped a drive shaft.

Cheers Andy

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topcatcustom
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Post by topcatcustom »

I'm hoping that wont happen to me- the 2wd Sierra Cossy ones are a good inch thick! Would be good to see you and the car if you make it, then I can look at a tidy install!!!
TC

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topcatcustom
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Post by topcatcustom »

Looks like the heads might be coming off already... excessive pressure in cooling system pushing water out, lifting the pressure relief lever on the Stant rad cap releases loads of air and the water level is about an inch lower than it was this morning :cry:

So I'm 99% sure its either head gasket (pray) or slipped liner. If it is then why oh why did I sell my spare 3.9 block :roll:

Typical- mag feature on friday too with photographer and journalist coming down, do I leave it till then and strip the heads off after or go for it tomorrow after work???
TC

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