Hybrid Engine Project

[iswinkels]

I've started to get a little more serious with building my mate Wibble's wrx headded vw hybrid engine. The project has been "under development" for about 2-3 months...

After a lot of measuring, a bit of design with autocad and some cardboard templates i've finally got a head-stud conversion system that will work.

The aluminium head plates that block off the water cooling galeries and oil feed to the head were CNC machined at my work. The 12mm steel stud adapters I had water jet cut.

The plan is to use 8 x 10mm high tensile bolts to torque the stud plates down to 25ft-lb. Then 6 12mm high tensile bolts come through the head plates from the bottom of the plate to bolt on the wrx heads to 30ft-lb.

The cam drive system will involve machining up some new hubs that are longer to account for the extended offset needed to get the timing belt to drive off a pully in front of the standard power pully. It will actually work out pretty well as the intake and exhaust cam timing will be fully adjustable. Save to say i've learnt a lot in the past few weeks about how cam timing works in a 4 stroke engine. Its been like craming for an exam.

The idea isn't new. Someone did a simular conversion on a type 4 engine on some speedway car in the UK, and they made 400+ hp running it turbocharged.

Lubrication for the OHC heads will come from what is normally the full flow oil return. The oil return from the heads will return to the sump via fittings that will end up screwed into two of the pushrods tube holes. The other two will (each side will be blocked off).

So... Here we see Wibble's shiny new empi bubbletop aluminium case. 10mm head studs, 94mm barrels, clearanced and full flowed, some wrx heads courtasy of my mate Reub, and a pair of 94mm barrels



Here is the CNC machined and waterjet cut head and stud plates.



This is the barrels slipped into the case with the head stud and alloy head plate slipped on.



This is a pic of one head sitting on top of the whole lot.



And again from another angle.



The eventual goal of this engine is 12:1 compression, 7300 RPM, and 200+ naturally aspirated HP. 2180cc (78.4x94).

The prototype is using turbo heads so the compression will be closer to 9:1, but that will do for a prototype. We'll switch to EJ20 2000 model naturally aspirated heads later on to crank up the compression. The wrx heads are definatly a lot more suited to a forced induction application. (55cc combustion chambers) The potential for the prototype would be amazing with a pair of GTR R33 turbos's on it. I'd figure 400-450 HP would be an achievable figure if we got the flywheel wedgemated.

As for whats next, i've got to trial fit the other side of the engine and then buy some high tensile bolts to trial bolt it all together, which is a project for next weekend.

As for my car, its stripped again and is having the flaws and a few scratches fixed. Should be at show quality in 3 weeks, just in time for a car show on the 29th of October.

I'll keep you all posted as to the progress of both projects.

Cheers,

[iswinkels]

Today I sorted out the other side of the engine. I'll be picking up head studs this week so I can bolt it all together, and start working on the timing belt drive and tension system.

Here's another pic..

[73notch]

the wrx bore spacing is the same?

[iswinkels]

Yes the spacing is the same. I can't confirm it but I think the EJ22 heads have the same spacing as a type 4 engine too. There was a 450hp speedway engine built in the UK that used a "version" of subaru heads that was built on a type 4 block.

[jifop]

wow thats an amazing project! keep us posted

[Guest]

wow, thats really thinkin outside the box( vw box that is) truly awesome.

[iswinkels]

Well today the machine shop guys at work made me a timing belt drive pully, so i've been able to start nutting out how to drive the cams, change the pully offsets and drive the fan/alternator. Dam its good to work for an engineering company sometimes!

The system will use two idlers and one tensioner. The idler on the right will drive a v belt pully which inturn drives the alternator. These will mount off an alloy or steel plate (undecided yet) that bolts to the crank case from the three rear engine mount points.

It looks a little abstract at the moment, but it should work ok and will make more sense once its assembled.

The next step is making the custom cam gears. And here's some pictures!





Cheers,

[iswinkels]

Today I scored a set of 4 timing belt pully's and a set of tensioners and idle pullys so this has allowed me to work out exactly how the timing belt system needs to go together.

For the moment the duel pulleys on each cam are bolted on, but they will be welded together and then machined back to where they need to be to allow the belt to run squarely on the pulleys.

Tomorrow i hope to score a steel v belt pully from a wrecker thats about 5" in diameter to weld to the geared idler pully to serve as a drive for the alternator.

Then its on to making the backing plate that supports the tensioner wheels and serves as the back for the timing belt cover.

Here's a pic of the revised timing belt drive system.



Cheers,

[young]

Obviously a man with no fear. It looks great, good luck with it.
Can't wait till you're further along.

[mnsKmobi]

Obviously a man with no fear....

Oh, and a friendly machine shop!!!

[fortyeye]

Bump to the top ... this is a fascinating engine. Eager for updates.

[iswinkels]

So here's the latest update. The timing belt system is mostly sorted out.



The latest engineering challange is that i've outsmarted myself by going to an engine case that uses 10mm head studs. This means the grade 12 high tensile head stud bolts I was going to use have heads that are too big, and they don't allow the barrels to slide on through the stud adapter plates due to bolt head interference. The barrels will fit if I am able to machine 1mm off the outside of the bolts, but how do you machine grade 12 steel?

I've got an indermediate solution though that will allow me to get the heads bolted on and start messing with cam timing, and piston to valve clearance checks. With any luck by the end of this weekend there will be a crank with rods and pistons in the engine, and the heads bolted on.

[Rolf]

The barrels will fit if I am able to machine 1mm off the outside of the bolts, but how do you machine grade 12 steel?

In a lathe with a special tool steel chip in the chip holder, will work but the chips are expensive and the bolts are HARD. Or sand then down on a belt sander and rotate the bolts with a cordless drill while sanding. works like a charm
Done it LOTS of times with all grades incl grade 12.9. The bolts I have reduced in diameter and head height this way are allen head bolts. It's posible to remove the first 0,5-0,7 mm in the lathe, but them they relly gets hard. If more is needs to be removed I use the cordless drill and belt sander way.

Just my thoughts

Keep on the good work

Rolf, Denmark

[iswinkels]

Another update. I've finally got one of the two heads bolted on. This is the easy side done. The head studs on the left side of the engine are more complicated due to the cylinder offset. With any luck i'll get that side done tomorrow.

Ran out of time today on account for going to the local 1/8 mile drags.

Anyway, here's some pics. I'm only using 4 head studs for the mock up, but the final will use 6 like a normal subaru. They are 12mm HT and will end up being torqued to abotu 35ft-lb.

The two center and two front main bolts will be removed and longer studs fitted that will further strengthen the stud adapter plates. I'm toying with the idea of running thru studs on the center mains after i have the engine running once.



Check the size of the intake ports on the heads. They are about the same size as the intakes on competition eliminator heads and have room for porting too. The exhausts are 1.75" in diameter.



Cheers,

[iswinkels]

Well both cylinder heads are on now and its looking pretty good. The stud adapter plates came out quite well but I need to adjust part of the design so they clear certain sections of the case more easily.

I'll be geting one more set of plates machined before the engine goes together in its final form so it can be started. As it is at the moment it will allow me to install rods, pistons etc, and check the piston to valve clearances.




Here's a pic of the exhaust ports, close on 2" output size, so easily good for 8000 RPM.



One last pic.



Next on the list is to order a set of scat 5.7" rods with 3/8th rod bolts. I can then machine the barrels to restore the deck height to about 0.040".

The project is going to be on hold for a few weeks now because i'll be re-assembling my car after picking it up from the spray painters this wednesday with any luck. Be prepared for some tastey updates being posted for that too.

Cheers,