Just stamping my ticket so I get updates

 

Odd on the shop talking of grinding the pistons. I'd really have to question them on that, as pistons are not round etc., etc. or lend themselves to "grinding".
Generally, you check the piston sizes and they do vary a small amount yet fall in to the manufactures tolerances. You also have a small tolerance for piston to cylinder clearance. You then number the pistons and bore / hone the cylinder to match each specific piston. The differences in size generally aren't more then about .0005 but a good shop still hones to fit each individually and assembles the pistons on the appropriate rods to make sure they go back in the cylinder they were fitted to.

 

Odd on the shop talking of grinding the pistons. I'd really have to question them on that, as pistons are not round etc., etc. or lend themselves to "grinding".
Generally, you check the piston sizes and they do vary a small amount yet fall in to the manufactures tolerances. You also have a small tolerance for piston to cylinder clearance. You then number the pistons and bore / hone the cylinder to match each specific piston. The differences in size generally aren't more then about .0005 but a good shop still hones to fit each individually and assembles the pistons on the appropriate rods to make sure they go back in the cylinder they were fitted to.

the "grinding" of the pistons is to get them all the exact same weight.
it lets it rev faster and easier and its a process for balancing the engine, in race engines along with balancing they use the lightest valvetrain they can get so as it revs faster and higher the engine has less work to open/close valves, move the rockers, and on non overhead cam engines the pushods.

most shops these days actuall drill the inside of the piston removing material so the weigh the same. they usually start out within a few grams of eachother.

 

^good info there Younggun. Never knew about that but it makes perfect sense.

 

I understand about balancing an engine, adding / removing weight from the crank, and all that good stuff. If you re-read psguardians post that is not what he is referring to. And yes, drilling is often used to balance the pistons, not grinding. Actually, when balancing them you balance the complete reciprocating assembly....rods, crank, pistons, even rings are matched. Even better throwing the flywheel in to the mix but again that's not what he is referring to.
Piston clearance is usually built in to the piston. For instance, if you had a 4.000 bore and bored it .03 over you now have a 4.030 bore. If the manufacture suggests .002 piston clearance the piston should actually mic 4.028 so if you bored all cylinders to balls 4.030 you'd have your .002 clearance. Going back to manufacturing tolerances, if one piston were .0005 undersize, you'd have one cylinder with .0025 clearance.
Not really that big of deal on most engines but it would still be desireable to bore and hone that particular cylinder .0005 undersize, or 4.0295 to dial in the .002 clearance.
Anyone I've known (including me) does match cylinders to pistons, they do not "grind" a piston.
Couple exceptions. Cat 3208 diesels actually have you hone one cylinder for even additional clearance over the remaining 7 cylinders! Kind of a ghetto approach to remedy a piston scoring problem they had in that one cylinder. Minneapolis Moline pistons come on size. Instead of the piston having the clearance built in to it, you add the clearance to the bore. Example if it were a 4.750 piston and you went .03 over, you hone the cylinder to 4.753, unlike the previous example.
Sorry for the long post, engine machining has always been one of my interests.

 

I may have poorly translated what the shop told me, it was all handed to me in a bit of an info flood before the guy left for the day. They did mention matching piston to cylinder which is the main reason they are waiting for my pistons (didn't come today so I'm hoping tomorrow). I took that to mean they would be matching the pistons to each other in diameter, this is my first interaction with a machine shop so I very well could have misinterpreted what was said 'at me' rather then explained 'to me', what you say makes more sense Airhead rider. Also younggun a very good explanation of 'balance & blueprinting' but no that is not being done to this engine for a few reasons; A- it's spendy & I'm poor, B- the benefits only begin to show themselves @ the top 1/3-1/4 of the TAC, C- those benefits fade (to varying degrees, the more blueprinting done the longer the effect lasts) after 10-20k miles anyway. Thank you for looking out for me on the 'is the shop being shady' points folks.

So aside from balancing & blueprinting does anyone have an idea for improvements to this engine? The head will be rebuilt in the next week or two & I need ideas/info ahead of my trip for parts & shop work.

I have heard of people putting spacers between the Throttle-Body & the intake manifolds for a boost in torque on other rigs, has anyone tried this on a 4ZE1?

Any 'bolt-on' add-ons or upgrades to current equip that can be done?

Thanks,
~psguardian

 

As far as I know, the single best power upgrade you can make on the 2.6L is to have the ECM re-chipped. I have heard that Jet Chips in CA has done it and that the power increase was noticably greater. Other than that, most mods are incremental at best. You can consider the basics like headers and so forth but mostly you just get more low end torque from that. IDK really. The best you could do (and it sounds like you are doing it) is to rebuilt that sucker and tune it out as best you can. When they are running tight, they can be quite responsive. Oh why oh why did isuzu set those injectors to fire all at once and not be timed? :x

 

Also worth mentioning going over the cam timing with a fine tooth comb. Much has been written by Squatch and others about not taking the timing mark on the harmonic balancer as gospel as it can be off. No better time to establish accurate valve timing then at the time of rebuild.

 

As far as I know, the single best power upgrade you can make on the 2.6L is to have the ECM re-chipped. I have heard that Jet Chips in CA has done it and that the power increase was noticably greater. Other than that, most mods are incremental at best. You can consider the basics like headers and so forth but mostly you just get more low end torque from that. IDK really. The best you could do (and it sounds like you are doing it) is to rebuilt that sucker and tune it out as best you can. When they are running tight, they can be quite responsive. Oh why oh why did isuzu set those injectors to fire all at once and not be timed? :x

For the trail I really am looking for more low end Torque stusvend, so these are exactly the kinds of things I'm looking for. Thanks for pointing them out, didn't even think of a chip upgrade, checked out the site Jet Performance Products (had to lie & tell the site I had a 1990 because if 1989 is chosen Isuzu is not on the list) & decided to call them (48hr email reply time) about their 'Import ECU Upgrade Kit Part #: 65001' (currently $329.00). I asked them a few important questions & here for everyone with this engine, here are the answers;

1. What kind of torque gains can be made on a fresh engine?
___A. 15hp & 12ft/lb.
2. How 'bout with a w/delta cam?
___A. Give us the specs of your CAM we can give you an est.
3. Can the ECM can be programmed for TIMED INJECTION to sync up with the intake stroke of each cylinder?
___A. No sadly the only thing we can adjust is fuel/air mixture (ratios not per injector timing) & the electronic timing advance (if applicable).

Soooo, I think this may be an addition to the menu @ a later date.

Also worth mentioning going over the cam timing with a fine tooth comb. Much has been written by Squatch and others about not taking the timing mark on the harmonic balancer as gospel as it can be off. No better time to establish accurate valve timing then at the time of rebuild.

Now this is a Fine Idea Airhead rider, I will search the forum on timing from the CAM not the H.B. & post a link here. This should help me get the most out of my new CAM (when I get to the head lol)

~psguardian

 

You can't get an ECM redo for an 88 Tooper II. Jet Chips will do later years, but not 1988. You don't need to remap the ECM, you just have to boost the fuel pressure to 59 psi. Also, instead of doing this whole rebuild, just go to JIS and get a rebuilt short block for $599. They do a great job. For less than $1,000 you can have a new engine, top and bottom, ready for your performance mods as per my article of February 20, 2010.

 

You can't get an ECM redo for an 88 Tooper II. Jet Chips will do later years, but not 1988. You don't need to remap the ECM, you just have to boost the fuel pressure to 59 psi. Also, instead of doing this whole rebuild, just go to JIS and get a rebuilt short block for $599. They do a great job. For less than $1,000 you can have a new engine, top and bottom, ready for your performance mods as per my article of February 20, 2010.

Have you called Jet? The website doesn't properly match the in-house databases, I called & pointed out the pre '90 4ze1 is the same as a post '90 4ze1 (excluding the 92/93 head changes). They said yes we see that, I'm sorry the website doesn't reflect this, we will inform the web guys of the error. The full line of 4ze1 engines are supported by the product/service listed in my previous post.

Boosting the fuel system pressure would really only accomplish a portion of what I am gaining, increased pressure would increase per pulse fuel delivery, mildly increase HP & maybe torque, lower MPG, make the ecm redo its own fuel/air ratio due to richer exhaust, this is great for a 'quick fix' to your Modding urges but not the same final output gains as what I'm doing, thanks for pointing it out though

Where were you with that longblock a month ago when I started panning all this?! LoL sounds like a good deal. Oh well, I'm in Oregon so shipping probly would have killled the initial savings anyway.

~psguardian

 

I have indeed called Jet, and they were adamant that their chip would not work. You are right that merely boosting fuel pressure won't help, but with the new head and increased compression ratio and decreased air restriction you get what feels like a 40 HP gain. I can burn the tires with this arrangement. What's funny about the engine block is that there is a $80 core charge, and it costs them more than that to have my old block returned. So they just put off sending the truck for it until they simply sent me the $80 and told me to junk the block.

 

I have indeed called Jet, and they were adamant that their chip would not work. You are right that merely boosting fuel pressure won't help, but with the new head and increased compression ratio and decreased air restriction you get what feels like a 40 HP gain. I can burn the tires with this arrangement. What's funny about the engine block is that there is a $80 core charge, and it costs them more than that to have my old block returned. So they just put off sending the truck for it until they simply sent me the $80 and told me to junk the block.

 

that's odd, just to be sure I am talking about the same thing you are, this is their "send us our ecm & we will re-chip it or re-flash it if the chips are soldered in" service, cost is $329 right? They told me '89 was covered I wonder why they would say no to 88 :?

~psguardian

 

Yep. I called, and begged, thinking that this would help. They said definitely no to upgrading my brain. They didn't say why. Again, you get WAY more power doing it with the 4ZD1 head and fuel pressure change, for about the same price.

 

I

Yep. I called, and begged, thinking that this would help. They said definitely no to upgrading my brain. They didn't say why. Again, you get WAY more power doing it with the 4ZD1 head and fuel pressure change, for about the same price.

I wonder if the Rep I got was just wrong then... *ponders*

About this head swap, I'm getting bored +0.040" so that's a compression ratio increase right there, can I still put in the 2.3l head with 2.6l timing set & a 260* CAM for the 2.6l?

If so, would I need to increase the fuel pressure? What are diff in stock vs high-flow fuel? What pump would I use? If you're set up like this what MPG do you get? What tranny / gears / tire size are you using?

~psguardian

 

if you raise the compression and you use the 2.3 head wouldnt it crack easier? its an aluminum head theyre not that strong

 

if you raise the compression and you use the 2.3 head wouldnt it crack easier? its an aluminum head theyre not that strong

On top of a stock 2.6L Block I could see using the 2.3L head living a long happy life, min unfortunately will be bored 0.040 over AND decking the head surface, these combined with probly having to resurface the head would probly result in a short lived head (man what a ride it would be though lol). I think to get running I'm going to go with a 2.6L head & try to get me a beefed up CAM.

88trouperII I would still like the specs on your drive train for comparison, if you're willing to share

~psguardian

 

PARTS !!!

______________________________________ Christmas Time All Over Again ______________________________________

_____________________________________________ Mmmm Parts _____________________________________________

____The PISTONS that I have been waiting a week for !!!!____

Rushed home & took the Pistons & Rod bearings to the machinist so they could begin cylinder matched boring/honing & hang the Rods from the Pistons for me, also threw in setting my Freeze Plugs free! Should have the short block back on my stand by Friday, Monday if they get any busier this week.

~psguardian

 

The block & crank are home from machining! Time to build the head! Any tips/tricks for better torque out of the 2.6L? Any valve or porting guides/tricks ya'll can point me towards?

~psguardian

 

Not an expert by any means, but at a minimum you may want to go over the ports and runners and smooth up some of the casting flash and stuff that looks like it SHOULDN'T be there. Just don't open things up .
Fit up the intake gaskets and make sure there aren't any bits sticking up restricting the air flow.I have seen a gasket set once that had the diameters about a 1/4" smaller than the intake runners on one side.
Don't go to the extreme to max out the diameters to all match the biggest hole or you will mess something up.

 

Good idea, I was considering this. Since I am decked & bored 0.040" on the block & a milled/decked on. The head should I trim the head gasket to head, block, or leave it hanging into the cylinder?

~psguardian

 

Are they not providing an oversized head gasket?

 

.....should I trim the head gasket to head, block, or leave it hanging into the cylinder?

~psguardian

^^Ignore the NEWB above this line^^

Are they not providing an oversized head gasket?

After checking the head gasket IS for a 0.040" over bore lol.

It was not mentioned in the list of size specific parts, they just automatically matched it to my piston overbore *whew*

~psguardian

 

These days you never know. Glad to see you checked and that they had you covered.