High Compression Turbo D16A6. Take 2.

This is what happens to OE D16 Rods when you add compression (11:1) and boost (10 psi). Conventional wisdom says that they are good to 200 HP, but that's on typical builds. My build made a lot more torque than a typical build, so while I'm 25 HP short of conventional wisdom, I'm probably 50 ft-lbs stronger than those motors. Since torque and cylinder pressure are directly related, it makes sense that a torquey motor will bend rods at a lower HP. Note - this isn't due to detonation. The pistons look great. Just pushed the rods way past their happy point:

Anyway, the rods all doing their best impression of pretzels meant that it was time to build a "real" bottom end. Real = a Golden Eagle Block Guard welded in, Eagle Rods, SRP Pistons, and ACL Bearings. It should be good to ~500 HP, not that I'll ever approach that in an autox car.

So - the teardown...

OE Rods self-clearancing:

Main Bearings had seen better days. Of course, these are the original 200K mile bearings that have seen much abuse, so that's fair. This was the worst one:

Clearancing for the Eagles:

Clearanced and cleaned:

While I had a grinder in my hand and a bare block in front of me, I went ahead and removed all of the flashing that I could get to. Internally this means better oil drainback. Externally it means fewer busted knuckles when wrenching.

Golden Eagle Block Guard placed 1/4" below the deck and welded in:

An then it was off to the machine shop to be bored and decked, since welding in the block guard can distort the cylinders. Local NAPA did a good job, and I got it back only a few days later.

The Build...

No wonder D motors weigh nothing. The block itself is only 37#. Note - this is a .5mm overbore.

Shot of the Bore / Hone / Deck

This is what $800 worth of sexy looks like. The Spiral Locks that hold these together are a BITCH to put in. It's easier if you follow the directions on the Keith Black website rather than trying to do it JE's way.

My newly invented, patent pending, "Don't-drop-the-pistons-when-you-flip-the-motor-tool"

To get the most accurate clamping pressure, rather than torque the rod bolts it is preferable to measure them for stretch. This involves a stretch gauge, which is just a dial indicator, a little fixture, and a couple of centers that, in theory, sit in the divots in the ends of the bolts. Unfortunately, the Summit gauge I got was a POS. Rather than having a large sphere that would sit in the cone of the divots, it had small ones that sat at the bottom of it. This made it very inaccurate. The guy who designed this thing needed to spend another week in metrology class. Anywho, I decided that I could use it if I got some ~1/8" ball bearings to use as my datums. FYI, while Home Depot doesn't think they sell ball bearings, they do. They just house them inside swivel casters. $2.79 later and I've got precision centers for my stretch gauge on Easter morning...

Bottom end getting buttoned up.

Sexy sexy.

TDC / BDC.

A few pics of porting the oil pump. Supposedly this cuts down on high RPM cavitation and helps the flow. It was pretty ugly, so the flow definitely improved through these areas. Whether it is needed or not, who knows. But it was free and it can't hurt.

Bottom end all buttoned up.

Transfer pipe, breather box, oil feed (BSPT to AN fitting that feeds a manifold mounted on the firewall), water temp sensor, and oil filter in place. Water pump, timing belt tensioner, lower timing pulley in place.

Earlier I had wondered if the OE head gasket would handle the overbore (.5mm). Here it is. 75.85mm. Standard is 75mm, I'm 75.5mm. This is the 5 layer TSB gasket BTW.

I got the head cleaned up and ready to go on. I think it's ready for the head, timing belt, etc. I'm tired though and didn't want to do something stupid / leave something out. I'll do the top end tomorrow night...

looks good dude. What's your new compression ratio going to be? Engine management? Turbo choice?

does this mean you'll have even more awesome dyno charts posted up soon?

I dont even like Honda and I think this thread is cool. Well done sir.

Those bent rods are an interesting way to get lower compression for your turbo motor.

Call me a ponce, but...

DILYSI Dave wrote:

I would have a damn hard time putting oil & gas into something that pristine. Wow.

Awesome! I wish I had your engine building skills!

Looking forward to more progress.

Brust wrote: looks good dude. What's your new compression ratio going to be? Engine management? Turbo choice?

Should still be approximately 11:1. The block was decked a few thousandths just to clean it up and ensure flatness after welding in the block guard. Not a significant amount though.

Engine management is Zdyne for now. After tuning with the Zdyne though, I see megasquirt in my future. Zdyne isn't bad, but since it's based on the OE ECU it has good resolution where Honda wants it (below 2500 RPM) and pretty crappy resolution here the motor now operates (above 4000 RPM).

Turbo is a T25 off of a Mitsubishi Eclipse.

thatsnowinnebago wrote: does this mean you'll have even more awesome dyno charts posted up soon?

In theory the dyno charts shouldn't be any different. The vital specs aren't changing - just the parts that get us there. That said, I don't know how long the rods were bent prior to teardown. I suspect that they gave up the ghost in the last couple of minutes of running, but there's a chance that their failure was progressive. As mw alluded to - the bent rods lower the compression ratio. If they were bent when it was on the dyno, then yes - the motor should be stronger now.

awesome man.

i had a small problem with bent rods too with my last SOHC stocker.

one ended up poking out the front to see what the haps was .

i love turbo D builds...great job man

Sick post. Wowee.

Wow, killer build and a nicely done thread! I know what you mean with Summit's engine building tools as well. I like your solution, I ended giving up and getting a second super-accurate torque wrench just for engine builds. Looking forward to the rest, good luck!

I'm curious as to why you're running such high compression?

small turbo (T25) = good low rpm torque, high compression = good turbo response and great high end power

Can't wait to see it running! (You should post some autox vids!) do you run in street mod?

ChesterRumble wrote: I'm curious as to why you're running such high compression?

To eliminate lag. Higher combustion pressures = higher exhaust velocity = less lag. Also, the higher compression helps the off-boost performance, also leading to a nicer torque curve.

Basically, I loved the elegance of a turbo, but hated the driving cynamics of every turbo car I'd ever driven. I wanted to get the power gain, but without the retarded torque curve.

It worked. The only real sacrifice is that you need some high octane fuel to keep things in check inside the engine, which is why I now run the car on E85. It is 105 Octane, and even with aggressive timing there is no knock, nor any signs of detonation.

DILYSI Dave wrote:

ChesterRumble wrote: I'm curious as to why you're running such high compression?

To eliminate lag. Higher combustion pressures = higher exhaust velocity = less lag. Also, the higher compression helps the off-boost performance, also leading to a nicer torque curve. Basically, I loved the elegance of a turbo, but hated the driving dynamics of every turbo car I'd ever driven. I wanted to get the power gain, but without the retarded torque curve. It worked. The only real sacrifice is that you need some high octane fuel to keep things in check inside the engine, which is why I now run the car on E85. It is 105 Octane, and even with aggressive timing there is no knock, nor any signs of detonation.

I kind of figured that was the reason it just surprised me with the first build and the OEM D series bottom end. Are there any options from Garrett as far as an appropriately sized turbo for your particular build? Something quicker spooling than the T25?

ChesterRumble wrote:

DILYSI Dave wrote:

ChesterRumble wrote: I'm curious as to why you're running such high compression?

To eliminate lag. Higher combustion pressures = higher exhaust velocity = less lag. Also, the higher compression helps the off-boost performance, also leading to a nicer torque curve. Basically, I loved the elegance of a turbo, but hated the driving dynamics of every turbo car I'd ever driven. I wanted to get the power gain, but without the retarded torque curve. It worked. The only real sacrifice is that you need some high octane fuel to keep things in check inside the engine, which is why I now run the car on E85. It is 105 Octane, and even with aggressive timing there is no knock, nor any signs of detonation.

I kind of figured that was the reason it just surprised me with the first build and the OEM D series bottom end. Are there any options from Garrett as far as an appropriately sized turbo for your particular build? Something quicker spooling than the T25?

I knew all along that I was on borrowed time with the OEM bottom end. I wanted to get enough run time out of it to prove out the build theory. So it did what it was supposed to do.

I've got a buddy who is an engineer at Honeywell (Garret) that is working with me to determine if a different turbo would be appropriate. The current thought is a GT28RS. It is slightly bigger, which will help up top where this one does fall off, but the ball bearing center should help me retain the awesome spool I've currently got.

That is awesome if you can find something sized for your build. I'm sure it's one helluva ride. I've always had a fondness for D series builds whether its a turbo or NA build.

They are so underrated and the power that Bisimoto has been able to pull out of the F/D series motors is just stunning.

E85 is a godsend for boost builds! I want to build another turbo car now that we have an E85 station in town.

Jay wrote: Call me a ponce, but... I would have a damn hard time putting oil & gas into something that pristine. Wow.

Agreed. That would look fantastic with a glass top over it and sitting in the middle of a living room!

Question: Why the block guard?

I have an extra D-series one lying around that i haven't used because i don't really trust them, on the pretense that they're not the same exact metal as the block/sleeves, so they don't have the same expansion/contraction properties.

I could very well be wrong, i just can't get my head around why they would make much difference.

Looks good. Now drop it in the Jeep.

looks really good. i like the idea of high compression + turbo.

do you have a link somewhere to the original build?

Dave, Give Turboedit a try... can modify the resolution if I remember right... and its just a chipped ecu also. Program is $free.99 also...

I love pictures. Thank you.