Proposed 7age (stroked) build - Am I on the right track?

[undercoverninja]

Ok so here is what I have so far, for a stroked 7age build on a "budget" (In quotes because it will still cost a lot, just not as near as much as it could).

Stock 7a bottom end and crank, con rod journals reground from 48mm to 42mm, bringing stroke to 91.5mm. Balanced and nitrided. Matching 135.5 mm long forged rods, 20mm full floating pins. Custom wiseco pistons (I will need to order, unsure how much this will cost, bound to be a lot...) of 25.15mm compression height and 2mm dome cc or as close as I can get to this. That will give me about 0.04" squish height with my head gasket. Dunno about valve clearances.

Head is smallport 4age, ported and (hks valve springs, kelford cams 284, shimless buckets) - to do after it is running with a stock head. Valves reseated/reconditioned 3 angle valve seat? Im unsure if this is needed. Adjustable cam gears. 0.5mm TRD metal head gasket.

ACL race bearings for the 4age to be used. New gaskets etc from some shitty ebay supplier.

Megasquirt ecu 52 pin diypnp, for connecting to a 7afe ecu harness.


Any comments? Am I on the right track? I worked out C/R as about 12.15, will be running 98 octane fuel. I would love to rev it to 8000, but looking at the numbers on my (erm aquired ) copy of engine analyzer pro, peak power for the kelford cams with the timing I had set is about 6500rpm anyway and at 8000rpm max piston speed is like 4800fpm...

[nick.parker]

Will the rods be custom as well? Stock 7AFE rod length is 132.5 - which you have acknowledged (in your calcs). Some websites offer to get Pauter Rods made slightly modified for the same price as the off the shelf rods. With your R/S ratio of 1.48, I would imagine the rev limit shouldn't be much higher than 6500rpm, based on anecdotal comments from other forums and charts of rod stroke ratios for production engines that I've seen.

[undercoverninja]

Will the rods be custom as well? Stock 7AFE rod length is 132.5 - which you have acknowledged (in your calcs). Some websites offer to get Pauter Rods made slightly modified for the same price as the off the shelf rods. With your R/S ratio of 1.48, I would imagine the rev limit shouldn't be much higher than 6500rpm, based on anecdotal comments from other forums and charts of rod stroke ratios for production engines that I've seen.

Yes, the rod stroke ratio might be an issue - I am unsure how much though, I think 7000rpm will have to be the rev limit at least - The max piston speed gets very high past that..

The rods are custom billet steel not forged oops, bought off a ae86drivingclub member for $400 or so, he made 3 sets.
I redid my calculations, 24.75mm is the target piston compression height. Wondering if I could make that from a 27.2034mm piston (Brian Crower) by machining the crown...

The con rod schematics:



Considering finding a used 1zzfe crank in good condition, and offset boring the cylinders. Each bore would need to be moved 0.75mm towards the center due to slightly different center to center spacing, and I would need 82mm oversize pistons, giving me 1930cc... but at the thinnest point of the cylinder walls, between cylinder 2 and 3, I would be taking off a good 2.5mm total, 0.5mm more then reboring it to 83mm with the stock crank, which is the max anyone recommends.

Then there is the question of everything lining up... a few people have tried it or considered trying it, and the main journals are matching but the block needs to be machined for the counterweights to pass... Or so I have heard.

I would also have to take 2mm off the diameter of the journals for the cod rods, in order to fit the ones I have.

Tried to contact brian crower about the specs of their pistons for their 4age stroker, but the compression height is ~2mm more then I need :/ and I haven't got an email back from wiseco about my enquiry. Mmmmh.

Anyhow, brain/idea dump. Hopefully I can get this project together eventually, and not just succeed in blowing up an engine xD

[Billzilla]

Any comments?

Get a 3SG, it'll be cheaper, easier, and you end up with a bigger engine as well.

[undercoverninja]

Get a 3SG, it'll be cheaper, easier, and you end up with a bigger engine as well.

Yer I figured that, I have a 4age and 7afe that just happen to be lying around however. Well if all else fails I will cut my losses and just buy a celica with a 3sge that I can get for cheap.. I'll try to get a quote from wiseco on custom pistons first though. This could very quickly turn into a money pit, one that might blow up in the first 1000km :S. A 9age would be fairly unique/enjoyable to have I think though (I am too much an optimist I think - but I can dream)