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petert

[Race_Prep] Never Ending Race Car Build

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welshpug

offset pin?

 

Not sure how people can sell parts that are so obviously wrong, or even make them!

Edited by welshpug

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petert

Block prep completed and ring gaps done.

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petert

Work on a head progressed. I remembered I had a semi-finished head tucked away with a box of bits. It was a pleasant surprise to find more in the box than I'd recalled stashing away. The exhaust valves were a mixed bag however. Whilst they were all new, from the same supplier, three had different collet positions, by a whopping 1.5mm. Luckily the collet position was favourable, unlike the other five, which required 2.9mm shims to get the desired seat pressure. This is common with the PAC springs. Here's a few shots of the head before final assembly.

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petert

Crankshaft in. Spins beautifully.

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petert

A bit further today. Pistons are in and rod bolts stretched.

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petert

Those piston pockets are deep. They ended up being a total 5cc of volume. With a 1.2mm copper gasket, I've ended up with approx. 11.7:1. Probably should have used 1.0mm and had 12:1. Anyway, head is on and torqued down.

Edited by petert

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camgti

Whens dyno day?

 

!!

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petert

Unplanned at this stage. Cams are in and timed up however. I managed to get 106/109 centrelines with two #2 pulleys and offset keys, saving the verniers for the sprint engine.

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camgti

Ive got a set of BBM adjustable pulleys if you want to use them? Theres just sitting there not being used!

 

Cam

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petert

It's all good thanks Cam. A pic of the finished engine and John "offering up" the gearbox to the engine.

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camgti

Awesome, looking great.

 

Cant wait to see how it goes!!

 

No problem Pete, offers there if you need them.

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petert

It goes ok! Good enough for a 1:08 at Wakefield today.

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camgti

Hang on what!

 

Its in and tuned

 

You went to wakefield and blasted a 1.08 out of the box?

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petert

Yep, the story on here was a week or so old, just foxing. We ran it in on the dyno last Wednesday night but didn't have enough time to change the oil and fine tune the top end mixtures. So dataloged it during qualifying, made a few adjustments and it was gold during Race 1. Not surprisingly, Parry can still just pull away down the straight, but that's ok as it was always an endurance motor. Next engine however.........

 

Also, I think the 1:08's is also more about the improved suspension/geometry. We previously struggled to do 1:09 with more hp.

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petert

I've started rebuilding the old solid lifter head. With an upgrade in cams I thought it would be wise to check valve head clearance at TDC. With the valves open at their lift @ TDC measurement, there's only 0.029" between them. Worse still, I have no idea what's going to happen after TDC. Will the inlet open faster than the exhaust closes? The only way to confirm is to fit an idler pulley to the head, along with a short belt and rotate the cams in phase.

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JeffR

Headgasket thickness (if any) in your calcs? A 1.2mm (0.048") would give enough clearance with solid lifters.

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welshpug

valve to valve is the concern, valve to piston is pretty straightforward really.

 

downside of large valves and inclined layouts.

 

not sure how similar to the later heads the mi is but i found i could get about 4 5mm on a gti6

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petert

Headgasket thickness (if any) in your calcs? A 1.2mm (0.048") would give enough clearance with solid lifters.

I normally work on 0.7 to 1.0mm. Thus 1.2mm in your case will be fine.

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petert

not sure how similar to the later heads the mi is but i found i could get about 4 5mm on a gti6

Valves are 36.5/30.0. Lift at TDC is 4.5/3.7mm. Way too close for comfort.

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JeffR

Has the block your measuring against been previously decked?

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petert

Cams too big for the valves. They touched.

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petert

I've done some more work on this solid head. I took 0.5mm off the exhaust valves and sunk them a tad, but there's still insufficient clearance to run the cams I'd planned. As a friend said, I was just too greedy. The only solution for this head is to reduce the cam duration, on both inlet and exhaust.

 

In the meantime, I went back to the hydraulic lifter engine we built as an interim solution. After fitting a new exhaust and injectors, we got the power up to a quite reasonable 140kW at the wheels. Ignore the RPM axis, the cut was at 7500. I love that flat torque curve. It should pull very hard out of the corners.

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JeffR

Great result. Did you change injectors because of max duty cycle or better spray pattern?

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petert

In preparation for E85 duty cycle and spray pattern.

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andy0075

Very nice car! With the wide arches it looks like mine. :-)

 

I wonder how much BHP you will gain with the E85. Two years ago i tryed the same on my MI16 race engine.

I mapped it first with 100 Octan fuel and then with E85.

The gain over 100 Octan fuel was only 2BHP and thus i have decided to go with the 100 Octan fuel.

 

On the first page you have written that you use 500lb springs on the rear. Is 500lb the spring rate of the spring

or is this measured direct on the wheel?

 

Andi

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