Suzuki Engine Rebuild Question

[Stephen]

As I gather parts for my engine rebuild this spring I had a question pop into my mind. I'm intending to bore the block over .020 and put high compression pistons in. With the increase in compression, should I be doing anything with the head? I'm putting an Iskenderian cam and heavy duty rockers in, but should I be doing anything else to handle the increase in compression and/or help increase performance gains? I've heard of shaving the head or decking the block, but I'm not sure if that is something I need to be concerned with.

 

[Greg]

Shaving the head will gain you more compression. Shaving the head also straightens the head if it's been overheated and has warped. If you're already bumping up the compression with pistons AND shaving the head, you may end up with too much compression and be forced to run high octane fuel. Has a machine shop checked the block & head to make sure they are straight? Make sure you're starting with good parts before you put it all together. What are the stock compression numbers compared to the high compression piston numbers?

Decking the block refers to machining the engine block so the piston height is maximized at TDC.

You could port match the intake & exhaust on the head with a die grinder. Take your intake & exhaust gaskets, place them on the head (after lining up the bolt holes), mark out the material you can see on the inside of the gasket and then remove the material up to the gasket. After that, try blend in the intake & exhaust ports further into the head for the best flow. The smoother, the better. Obviously you will want to disassemble the head totally and clean it up very, VERY good to remove any small pieces of material. May be best to have a machine shop clean it up after you've done some work to the head.

A 3 angle valve job is a good thing too, pretty common when you have machine work done.

I have no idea how well a Samurai head flows, but I would imagine there could be some small gains. Most of the difference may be at higher RPM's though, since you'd be opening up the ports and reducing velocity at low RPM's.

 

[STAG]

The smoother, the better.

And as far as material surface goes, for the exhaust, smoother is better, you want the exhast as smooth as glass. Ask any machine/racing shop that does porting and polishing and they will tell you that for the intake side, you want to have nice smooth contours (grind down any sharp corners etc to make a nice smooth bend) but as far as the surface of the material, you want it rough... This will cause some air "turbulence" on the intake side but this is what you want. Having a roughened up surface on the intake side has proven more power than a smoothened surface because the "turbulence" or "turmoil" causes a better air/fuel mix=better combustion.

And I second everything he said... and what I'll add to it is; make sure all your valves are seated perfectly. Having high-compression will be of no use if you have compression leaks due to poorly seated valves. And use a good-quality head gasket.

 

[Stephen]

Shaving the head will gain you more compression, but if you're already bumping it up with the pistions, I wouldn't bother... you may end up with too much compression and be forced to run high octane fuel. What are the stock compression numbers compared to the high compression piston numbers? Shaving the head also straightens the head if it's been overheated and has warped. Decking the block refers to machining the engine block so the piston height is maximized at TDC.

Thanks for the info on shaving and decking. I've never tried to rebuild an engine for any other reason than just to get it back running again, so this is new territory for me.
I'm not sure about the compression numbers, I'll have to check my manual and get back to you.

Has a machine shop checked the block & head to make sure they are straight? Make sure you're starting with good parts before you put it all together.

I haven't even pulled the engine yet, but I'll make sure to ask!

You could port match the intake & exhaust on the head with a die grinder. Take your intake & exhaust gaskets, place them on the head (after lining up the bolt holes), mark out the material you can see on the inside of the gasket and then remove the material up to the gasket. After that, try blend in the intake & exhaust ports further into the head for the best flow. The smoother, the better. Obviously you will want to disassemble the head totally and clean it up very, VERY good to remove any small pieces of material. May be best to have a machine shop clean it up after you've done some work to the head.

I was planning on doing this as I know that the ports are quite off from one another.

A 3 angle valve job is a good thing too, pretty common when you have machine work done.

Good to know.

I have no idea how well a Samurai head flows, but I would imagine there could be some small gains. Most of the difference may be at higher RPM's though, since you'd be opening up the ports and reducing velocity at low RPM's.

So will this be reducing my low end torque? I should make up any loss with my new gearing, but I don't want to lose too much on the low end.

 

[Greg]

... So will this be reducing my low end torque? I should make up any loss with my new gearing, but I don't want to lose too much on the low end.

I honestly don't know, it may, it may not. It all depends on the engine, which I know nothing about. The higher compression will help with your low end. Another idea for better bottom end is a heavier flywheel. You will have more rotating mass, which will make it harder to stall. It will rev slower, but that's where the head work, bigger camshaft and higher compression will shine.

Some others who have built & tweaked those motors may know what works and what does not, but I think port matching will help more than it hurts. From my limited experience with Samurais, in order to move they require RPM's. I don't think you will cause too many problems with a good port match.

 

[Greg]

And as far as material surface goes, for the exhaust, smoother is better, you want the exhast as smooth as glass. Ask any machine/racing shop that does porting and polishing and they will tell you that for the intake side, you want to have nice smooth contours (grind down any sharp corners etc to make a nice smooth bend) but as far as the surface of the material, you want it rough... This will cause some air "turbulence" on the intake side but this is what you want. Having a roughened up surface on the intake side has proven more power than a smoothened surface because the "turbulence" or "turmoil" causes a better air/fuel mix=better combustion.

And I second everything he said... and what I'll add to it is; make sure all your valves are seated perfectly. Having high-compression will be of no use if you have compression leaks due to poorly seated valves. And use a good-quality head gasket.

I should have expounded on that... the smoother the transition from where it was ported to the stock, untouched intake & exhaust runner, the better. Rather than a hogged out hole on the outside of the head and stock ports only 1/4" in.

I don't know how well a race-built engine compares to 1.3l of Samurai terror... but I know what you're saying.

 

[STAG]

I don't know how well a race-built engine compares to 1.3l of Samurai terror... but I know what you're saying.

......

 

[Tacoma]

Careful decking heads and blocks: Valve clearance can become an issue in a hurry, not to mention possible issues on overhead cam engines.

The extra 4hp you get will be super awesome on the hard stuff though.

 

[scoutabout]

Just put in a new hamster wheel.

 

[Greg]

Stephen, have you considered a VW diesel swap, rather than building the stock gas motor? If I were a Samurai guy ( ) building a rig that was going to see road time, I would be hard-pressed not to drop in an engine that made good torque, got great mileage and was something you could turn up easily.

 

[Stephen]

Stephen, have you considered a VW diesel swap, rather than building the stock gas motor? If I were a Samurai guy ( ) building a rig that was going to see road time, I would be hard-pressed not to drop in an engine that made good torque, got great mileage and was something you could turn up easily.

I've thought about that, but since I'm slightly insane (you know this) I want to keep this build as Samurai as possible.
I have plans in the future for your old Sami to be a diesel, but for my tin top I will be keeping it Suzuki.

 

[O'neal]

If you want to be a purist in keeping it suzuki how about a 1.6? You would gain power,torque and actually push that samurai around

 

[Greg]

I've thought about that, but since I'm slightly insane (you know this) I want to keep this build as Samurai as possible.
I have plans in the future for your old Sami to be a diesel, but for my tin top I will be keeping it Suzuki.

Understandable... I'm sure you're well aware of the VW diesel swap. Myself, I love diesels and want to play with a VW diesel someday. I would even consider a slightly built Sami with a 1.6l turbo diesel for tooling around in the hills.

 

[STAG]

Understandable... I'm sure you're well aware of the VW diesel swap. Myself, I love diesels and want to play with a VW diesel someday. I would even consider a slightly built Sami with a 1.6l turbo diesel for tooling around in the hills.

Someone must have watched Xtreme4x4...

 

[Greg]

Someone must have watched Xtreme4x4...

Rarely, not all ideas come from the TV.

My daily driver is a TDI Jetta and it rocks. I'd like to have a small 4x4 with a VW turbo diesel under the hood, I think they're great little motors.

 

[Tacoma]

Someone was selling a kit for that at EJS last year... I took a few pics, if I can only find the disc now... anyway, it was a clean swap, and I'm all for it.

 

[Greg]

Someone was selling a kit for that at EJS last year... I took a few pics, if I can only find the disc now... anyway, it was a clean swap, and I'm all for it.

There's a couple company's making VW diesel swap kits, they're pretty inexpensive & simple.

 

[STAG]

Then you can run it on Bio-Diesel as well! For all the hippies that cry over dead trees

 

[abhaulr1]

Make dure you read the cam specs. they will recomend valve springs that are right for the application. You need the right spring pressure for the valves so when you rev your hampsters they dont float the valves.
Dwayne

 

[Kiel]

You can always do what I did with my samurai. I decided not to waste the time rebuilding the 1.3 block. For the same money you can get about 15-20 horse power increase by using the 1.6 block. They look almost identical. If you already have accesories for the 1.3 head, you can swap your 1,3 head onto the 1.6 block like I did. Everything bolts right up. That is the way I kept my header and propane setup on the intake.