Ish_944

Hi!

Despite being new to posting here I've been reading rl for a while now. I got really interested in the hybrid stroker concept and I need a new engine now so maybe the time has come. I want a reliable street engine and I'll most likely keep it NA.

I have a couple of things to sort out including the total build price.
I've got to get new electronics (planning on augtronic) and a full rebuild so costs are going to run very high. Everything will be done by a workshop.
Another issue is the machine shop. Apparently most places cannot drill with such a big diameter in my part of Europe...

For now I'd like help with the following points:
1) I need a new engine. Would an early block be fine? Are there any differences between turbo and early/late NA castings that I should care for?
2) Is the block filler strictly recommended? Remember, I'm not aiming at the power levels of refresh951 and Blown_944. (This is cheap but might be nearly impossible to get/import.)
3) How did you guys seat the cylinder liners at the bottom of the engine? Do you have any pictures by any chance?
4) Can I retain my recently cleaned NA injectors or will they surely be insufficient?
5) Does anyone know a good european source for the pistons, rods and bearings? (Shipping and import taxes are a pain.)
6) Any other good advice?

Thanks a lot for all input in advance!

Dave W.

That should be a fun project! Block filler is not absolutely needed for an NA build but it helps add stability. One tradeoff from adding block filler is that the piston and bottom of the cylinder runs a little hotter so you need a little more clearance between piston and cylinder.

Ideally the sleeves will be flanged at the top to keep them from creeping down during use. The sleeves should also be press fit into the block. You should look for a shop that has experience installing sleeves since there's a few other details that need to be done right.

Since it's an NA build you have the option of using a Honda rod with a smaller journal, which will let you increase the stroke a little more, plus the smaller rod bearing will have slightly less friction. The pistons that match a longer stroke are also lighter which will further reduce friction in the engine.

Ish_944

Thanks for your post Dave!
The Honda rods are very interesting! Could you save me a bit of time searching by letting me know which engines are these for? Cheers!

Another question is what maximum compression ratio would you gents recommend with 98 (100) RON petrol and ARP head studs?

Dave W.

I def recommend higher compression, but it also depends on your tuning setup. What are you using to tune? If you have full control over the timing and fuel maps you can raise compression more.

Dave W.

I did a quick search and I found a rod that allows the crank to be offset ground by an extra 2mm stroke over the 'standard' hybrid stroker, or 88mm total stroke if you use a 2.5 crank as a starting point.
If you use 102.5mm pistons and 88mm stroke you get 2903cc displacement. For an NA build you can safely use a larger bore and get more displacement.
Can you get JE pistons in your country? Are 3.0 blocks and cranks available to you?

V2Rocket

Dave,
What rod might that be?
I am piling up parts for a stroker too.

blown 944

-the early block has thinner cylinders to start with
-For an NA application I wouldn't bother filling the block, however, I still believe in adding a very good oil cooler
-The sleeves seat against the main girdle area,. You need to make sure no native aluminum comes in contact with the new pistons. I would also recommend flanged sleeves left .002 above the deck surface.
-You will need larger injectors and a tuning method. Ford brown tops would be my first choice for you
- pistons and rods are plentiful here. Not sure what you will need to aquire them
-For an NA application, I would just go ahead and go with the longest stroke using the 3.0 crank to start


You may want to add some information regarding the final usage of the car

drive135mph

Great project, I can't wait to see what this turns into!!

Dave W.

OK I'm out, I had a dozen catalogs open this morning and now I can't find it.

Ish_944

Thanks to everybody for your valuable input!

I suspect rods and pistons will have to be imported but I should be able to get everything, like JE pistons, etc.

The goal of this project is to get a very reliable engine for a mainly street car. I'll also take it to track days and hopefully DE.
I will get rid of the afm, add a cam and better ignition. I reckon the block will not need to withstand more than 250 PS ever. I do not want to rev it over 7000 either. (Maybe 7500 if it really keeps making power but we are very far from worrying about this yet.)

I can -theoretically- buy just as well a 3l block but finding a 2.7l head is usually difficult and a lot more expensive. Would be a lot of fun, though! (On a side note I'd start worrying about vibrations on a -say- 3.5l four cylinder...)
So I'm planning to stick to a standard 2.5l block as a starting point. Btw, wouldn't I get a worse rod ratio with the 3l crank at this (honda) offset?

Tuning should be no problem. The augtronic (augmentautomotive.co.uk - no affiliation, just my current plan) can run in closed loop, so ignition timing, fueling & target afr are no issue.

With an even smaller journal size (honda) will the crank not be too weak? My mechanic is already concerned about this.

blown_944 shall I look for an 85.5 block to have thicker cylinder walls or do you think I should not be bothered?

Thanks again guys!

V2Rocket

DO you think it might be cheaper to have the engine built in the US and imported as a unit?
Since you'd be taxed based on declared value it might be easier than paying tax on every item with a published price.

For crank weakness, NASCAR engines run the same size rod journal and manage over 100HP/cylinder so it should be ok!

V2Rocket

The smallest journal I've been able to find in a production motor is the early Toyota 4AGE at 40mm, then they changed up to 42mm like some other Honda. ACL does make bearings for those engines but you'd need a custom rod to use that size since the Toyota rods are way too short...$1500/set from Carillo.

Ish_944

This might indeed make sense. I'll consider it!

Right, but if the material of the crank is different then it doesn't mean much... Still, I hope this will not be an issue. Makes me also wonder why did Porsche oversize it so much? I'd guess they had a good reason but you never know.

V2Rocket

purely speculation, but the 944 shares most rod dimensions and rod bearings with the 928 from which it is derived.

52mm is a little over 2" which is about where most 90* V8 motors of the era (remember the 928 engine was designed in the early 1970s) are with rod journals.

928 rods are a little narrower since they run side by side but my guess is they did it for part commonality = save money on production cost.

Ish_944

Yes, this sounds plausible.

So which block should I look for? Is an early a bad idea? Would I benefit from a turbo one compared to the late version?
As far as I know there are no differences between them except for the holes for the turbo's oiling and the different oil cooler setup.