88 GTU rebuild

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Old Mar 8, 2012 | 08:14 PM
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88 GTU rebuild

So mine took a crap finally, back in like Nov/Dec. Gettin to the rebuild. I've known it was pulling coolant for a while.

Here it is being lifted out of the car earlier this week:


After some time spent today stripping everything else off:


Those exhaust ports are off-white. Is that normal?

Looking in the exhaust ports, I can see water pooled in the front housing. Also, there's a lot of white/yellow crusty buildup on the front exhaust port.

The edges of the housings look good, no flaking that I can see from the ports.

I'm just taking my time on this. I have the cherry picker for a month. I'm gonna have to cut off the flywheel nut. 1200 ft/lbs industrial impact couldn't get it to budge. It tore apart my flywheel stopper (after photo), have another one on order.

Last edited by Jet-Lee; Mar 8, 2012 at 08:16 PM.
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Old Mar 8, 2012 | 10:09 PM
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Man that thing looks nasty... Good luck with the rebuild, any plans for it so far?
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Old Mar 8, 2012 | 10:42 PM
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It had just a hair under 200k on it. The pictures don't show ALL the crap that was caked on.

I got a Pineapple Racing Large Street Port Template that I'm thinking about doing to it. Wondering if it'd still pass smog with the porting and having both pre-cats gutted (they clogged a while ago).
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Old Mar 9, 2012 | 09:16 AM
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Hey Lee, I have a nice size Chisel and sledge hammer, to remove the rear nut. I also have a cherry picker here, and eng stand, @ palmtree. I have a feeling your front iron is going to be bad.

Guys @ palmtree can press your bearings and lap your irons. Lmk if you need anything. Jr.
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Old Mar 9, 2012 | 12:35 PM
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I appreciate the offers guys (Jr and Jaime). I'll definately give you guys a holler if I need anything. Prolly gonna need assistance with the vacuum/fuel lines, as I didn't take pictures before disassembly (stupid, I know), but that'll be after it's back in the car.

I have another flywheel nut, so I'm just gonna cut this one off, much easier.

I also have two other engines completely disassembled to sort through and assess the best pieces for the new engine. Gonna weigh all the rotors and get them matched as close as possible.
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Old Mar 9, 2012 | 01:17 PM
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I'm also simultaneously building the engine on the bike.

Different head/piston/jug.

Going from:
62cc chamber
1.715" diameter intake valve
1.480" diameter exhaust valve
9.2:1 c/r

Going to:
62cc chamber
1.810" diameter intake valves
1.575" diameter exhaust valve
10.54:1 c/r

This change will accentuate my already-installed cams, seeing as the cams came from the same bike as this jug/piston/head combination. Keeping the stock bore and stroke to keep it under 500cc (492cc to be exact), for bragging rights. Expecting ~40-45whp out of it (25whp stock, dyno'd 31whp with just intake/exhaust).

So...building two engines at once...a single cylinder *****-to-the-wall thumper...and a ported 13B.
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Old Mar 9, 2012 | 10:02 PM
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Cool, I have chiseled quite a few, like 20-30, I know it works too. I have to start the build on my t2 also. Good luck, we're here if you need any assistance,
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Old Mar 11, 2012 | 07:59 PM
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So, everything inside looks amazing! Except the front iron inner gasket lip is blown in 3 spots. The rear iron is blown in 1. From the other two engines, I have extra irons. Just gotta clean everything up and it'll go back together nicely.

Some coolant passages were completely clogged, likely causing overhearing in those spots.
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Old Mar 31, 2012 | 10:19 PM
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Yeah, I'm taking my time on it.

So this evening I ported my irons. That's not nearly as difficult as I thought it to be, reading about it. Maybe it's cause I've used Dremel's since my early teens, ported my own automotive/motorcycle heads, etc? But I ported all 6 ports in the time it took my girlfriend to shower.

Used Pineapple Racing's "Big StreetPort" template.

I started out with a really rough stone to get close to the edge, then a medium stone to get right at the edge, then a fine stone to smooth it all out and make it pretty.

Considering making a bridge slot in the 5th/6th ports and leaving the inserts in. It's a street car, a downtown car, I will leave it the inserts in regardless to keep my low end. Just thinking if I bridge the 5th/6th ports, it'll help that much more when those ports open, while having minimal effect on low end power.

Last edited by Jet-Lee; Mar 31, 2012 at 10:22 PM.
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Old Mar 31, 2012 | 11:07 PM
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Never, ever, ever, ever, ever, EVER, Bridge an aux port. You gain NO power, and it is just a waste. Where's Rotarygod when you need him?
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Old Apr 1, 2012 | 09:35 AM
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Can you give a reason or specifics why it gains no power?

More often than not, more air + more fuel = more power.

If RotaryGod is that Aaron Cake fella, I'm not interested in his opinion. He's "done it before", but it was on a turbo car, not an N/A; different physics.
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Old Apr 1, 2012 | 10:24 AM
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Not trying to be a dick, but just seeing "Don't do it" isn't enough.

I can't see the pictures here: http://www.nopistons.com/showthread.php?t=73482 (yes I'm registered)

What is the reason that it doesn't work?

As said in the link above, it allows some of the mixture to flow into the trailing combustion chamber. That makes no sense to me. If the port is closed at the same time as the aux port, there's no more crossflow than the aux port itself would allow (my aux ports got little-to-no reshaping). Unless the BP is open longer than the aux port?

Air flow through the cylindrical port can actually draw a vacuum on the BP opening. This I believe. What if I were to make a little flap inside the port sleeve to help redirect air through that BP? This would also induce a tumbling airflow into the main aux port.


I'm not some little kid with money, I'm a working adult with a lack of. So I'm not looking to do a full BP with custom exhaust/intake/ecu/etc, just something better on the street that'll scream up high as well. No turbo either. You can also use big words with me, I work with mechanical and structural engineers every day (I do the ME's job, he just signs the drawings).

I understand piston engines to the nth degree. I understand cams and valve openings. I know your thought is "These aren't piston engines." I know. They're still an air pump. I understand that the port shape dictates open/close times as well as overall area, similar to how a cam dictates the same in a piston engine. This still doesn't tell me why an aux port bridge is bad.

Last edited by Jet-Lee; Apr 1, 2012 at 10:30 AM.
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Old Apr 7, 2012 | 04:10 PM
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Reading and reading, I've seen that the results are subpar.

I'd still like to investigate why it doesn't work and maybe try to remedy that.

Does any one know why it actually hurts performance to add that bridge in there?

Looking for intelligent conversation, not "because I said so".
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Old Apr 8, 2012 | 06:23 PM
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Well, shortblock is together. Went pretty smoothly.
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Old Apr 9, 2012 | 03:13 PM
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So I have four or five housings with blown-out coolant seal supports. Are the repairable or trash?

If trash, I may just use them as anvils and smash crap against them.
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Old Apr 9, 2012 | 03:46 PM
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Irons, not housings
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Old Apr 10, 2012 | 10:25 AM
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Hey lee, na ones are trash. If they were turbo it would be worth keeping and welding the coolant seal groove. They will crack, they're cast iron, recycle them.
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Old Apr 10, 2012 | 05:21 PM
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Gtu for the win !!!!!!! I love my gtu !!!!
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Old Apr 25, 2012 | 03:01 PM
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Recycle value isn't worth my time ($.12/lb). Like I said, I'll just use them as anvils or something at the house.

Most of the engine is together and ready to go back into the car. My new OMP lines come in today. Those will go on and then the driver-side motor mount and it's ready to drop in. After it's in the car, I just have to connect all the electrical, mount up the p/s and a/c, the UIM, and all that accessory stuff and she should be good to go.

Hope to have it running in the next couple weeks.
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Old Apr 30, 2012 | 07:01 PM
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IT'S ALIVE!!!

WWOOOOOOOOOOOOOOOOOOOOOO!!!!!!!!!!!!!!!!!!

*dancing*
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Old Jul 3, 2013 | 10:20 AM
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So 7000 miles later and I think it's finally "broken in". My mileage jumped from 13 to 20 mpg.

It's had two oil changes, one at 2000 miles and one at 5000 miles. Next one at 8000 miles. The oil comes out looking almost brand new, is that a good sign? I run premix in it, with the stock (mechanical) OMP in place as well.

Now just chasing down little gremlins and rattles here and there. Replaced power steering, replaced a/c, replacing bushings one by one, etc, etc.
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