sorry dd, i didnt look down that far. maybe u can answer my question about the a14 crank in a15? and do the rods and pistons match up for this setup, i think the extra disp shoud give a few extra hp also.

Quote:

The A14 & A15 block are dimentionally the same, however the A14 used a shorter stroke. The rods were the same for both too. If you used an A14 crank with A15 pistons, you will find that the pistons do not reach the top of the block at top dead center. This means that the compression will be quite a bit lower which would be good for higher boost pressures, but the cast pistons are likely to be hard pressed to hang in there at the higher end of the performance range.

If you are going to use cast pistons, then keep the boost somewhere between 5 & 8lbs. for maximum piston life.
I'm sure that others who run engines with boost can tell you what works best.

thanks dodgeman, ur info is very helpful, i just needed someone to tell me this works for sure. wat about forged pistons are these very expenzive for a a15? sorry bout all the questions im just trying to gather info so once i have moeny i can do everything straight away.
is it worth going to these measures, or will i get the same performance from a a14?

If you use the A14 crank in an A15, you effectively get an A14 with lower compression.

If you use an A15 you get a 7% bigger engine to start with, meaning more low-speed power. Top end power will be the same, since they use the same cylinder head. With a steel shim to control compression ratio, you can crank up the boost. Or leave the c/r alone, for better off-idle power and limit the boost.

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if you're going to limit yourself to 5lb boost, you better not drop the CR at all! Most factory turbo cars run at least 7 or 8lb, and cast pistons will normally be fine to double that as long as you don't have any detonation/mixture problems. Especially in a street car that would only rarely see those boost levels, and then only for very short periods of time. But good tuning is the key to the engine's survival.

We used an ACL 'head saver' shim on a turbo motor a few years ago. For less than $30 (plus $10 for a can of Hylomar sealant) it is definitely the cheapest option.

Hey there..

Great thread going here!

Does anyone actually have any Diagrams/bluprints/plans on specs' and how to go about getting your engine s/charged?

This is such great stuff - agze ? Roots? Where to start? Any advice or how to's?


Cheers

yeah not a bad thread when u read through it, should help more ppl than me out, just another questionor two.
where are these shims sold?
maybe itd just be easier to use that.
ohh and how would i limit boost on a draw through seeing as though u cant have a blow off valve, ive heard the v8 blown engines have some kind of purge valve or something???
thanks guys i know my questions must be getting annoying by now.

Its easy to limit/change your boost , all youve got to do is change the crank pulley size. The pressure out type valves are more for backfire protection, if you bleed off unwanted boost on a draw through system
youd be venting explosive vapors into your engine bay! Then youd only need a frayed ht lead and youd have some real problems. I think it may be possible to loop charge this back into the air cleaner, but Im not 100%
sure . Anyway the best solution is to run the right size pulley . Im starting with 1:1
ratio to begin with and going from there.
You should be able to buy off the shelf (after market) pulleys to suit the boost that you want to run. What size donk is your
blower off?

yeah i know all u gotta do is limit pulley size but surely the boost is going to rise real high once u get to 6 grand ???
i think the blower i wanna use is off a 2litre

Hey guys, sorry for the delay in getting back into this thread- holidays with the missus.
Anyhow, to answer a few questions that I have noted since my return. I put HEAPS of research into the S/Charging of my a14... too much to be honest, but 1 thing that i learnt was that you cannot take short cuts. Placing shims and spacers on the head to lower compression will not last long and cause more pain with air/compression leaks. Either forged or specially made pistons to lower the comp. is the only way to go.
The other thing is the size of the carby is almost immaterial, once that the s/charger begins to suck, baby, the fuel will be there to meet it. I am using a 2-inch SU off a 1985 Jaguar (from a twin set-up originally- 4.2 ltire) and it flows more fuel than is necessary. I originally tried a 1.5 inch SU and the flow rates were almost the same. I only opted for the 2-inch because it was in better condition.
Tuning was done very methodically according to the SU manual and I now have a needle profile that I can replace at any time if need be...
More later gotta go - photos soon!