Engine Rebuild Preparation

[S30Driver]

1 hour ago, Av8ferg said:

Do you know the compression ratio you’re going to get with an N47 head and flattop pistons, I’m just not sure what it would be? Looks like right now with dished pistons you would be 8.29:1.
I’m going to go with the P 79 head and flat top pistons.
Your chamber will be 9cc smaller than with the P79 and flat tops and that head has 8.82:1 CR.
 

Should be about  9.7 : 1  CR with the stock gasket thickness.   

[madkaw]

Does the bottom end need rebuilt, or you are just wanting to try it?!The bottom ends are about bullet proof unless it’s been neglected . Should be able to tell that by how clean the inside of the valve cover looks. Does it use or blow smoke? You might pull the head off and still see the cross hatch marks in the cylinders. I’ve seen it on a  motor with 100k +

You could save $$ and time and aggravation and less down time with your car by not touching the short block except gaskets . You could improve CR with a smaller combustion chamber head .  Instead of rebuilding that head you could put money towards a different head .

Facing the block? Probably won’t need decked either. 

Now the head should be resurfaced if it has any defects or just for the HG longevity.

Shorter valve seals or different valve springs for anything more then 460 lift cam. Probably get away with stock seals up to 480. 

Just throwing it out there

 

[240260280]

I see you are in Kanata area?  I am in NS but work for a telecomcompany HQ'd there.  I may be able to stop by every now and then to lend a hand.   Having a good set of tools is important.

 

Below (attached) is a software tool for doing initial engine configurations. It is a zipped  html file. 

 

 

 

 

S30 Engine Modeller V4.zip

[grannyknot]

21 hours ago, cronoz78 said:

I have been told that the most experienced engine builders are on this forum so I thought I might get some help and direction.

Like I said, these guys are the best.  That s30 engine calculator above that 240260280 posted is not only a great tool but lots of fun mixing and matching, swapping heads and pistons to see how much potential power you can squeeze out.  I know you are seeking a fairly mild boost in power but it shows you what is possible and power creep is addictive.

One thing that I have read many times on Z forums is that the L28 engine can be just as well mannered with a stage 3 cam as a stage 1,  that a stage 3 camed engine can have a smooth idle with more oomph with no penalties.

It would be interesting to hear what anybody has to say about the stage 1 - stage 3 debate.

[madkaw]

48 minutes ago, grannyknot said:

Like I said, these guys are the best.  That s30 engine calculator above that 240260280 posted is not only a great tool but lots of fun mixing and matching, swapping heads and pistons to see how much potential power you can squeeze out.  I know you are seeking a fairly mild boost in power but it shows you what is possible and power creep is addictive.

One thing that I have read many times on Z forums is that the L28 engine can be just as well mannered with a stage 3 cam as a stage 1,  that a stage 3 camed engine can have a smooth idle with more oomph with no penalties.

It would be interesting to hear what anybody has to say about the stage 1 - stage 3 debate.

To this point I would say go as big as a stage 3 . I know Chickenman is running a pretty large cam with the Bosch EFI with a little tweaking . Idle shouldnt be an issue , but can’t swear to that with the stock EFI. Probably with be a bit more stinky at idle. 

A 39cc chamber will get you around 9:1 

[cronoz78]

madkaw: 
Honestly the car runs good considering the mileage and age. Whatever I'm doing is because I have the time and space for the next few mths. The rear crank seal leaks, rear transmission seal leaks, oil pan.  I'm only doing these things since I have the time and space now.  what I dont want is to have that car have a problem further down the road where it is not drive able and I don't have time to really get into it.  Its for convenience right now thats all.  I'm the first to say "if it aint broke don't fix it" which is why Im having a hard time moving fwd with this. I hear what your saying though and very aware.  What I need to do is get the car out of storage (May) and look at these things again. run these compression tests ect. I have a camera scope i can send in the sparkplug hole to take a peek as well.
Facing = Decking (some people say facing)

grannyknot: How fancy to meet you here as well! lol

 

[madkaw]

54 minutes ago, cronoz78 said:

madkaw: 
Honestly the car runs good considering the mileage and age. Whatever I'm doing is because I have the time and space for the next few mths. The rear crank seal leaks, rear transmission seal leaks, oil pan.  I'm only doing these things since I have the time and space now.  what I dont want is to have that car have a problem further down the road where it is not drive able and I don't have time to really get into it.  Its for convenience right now thats all.  I'm the first to say "if it aint broke don't fix it" which is why Im having a hard time moving fwd with this. I hear what your saying though and very aware.  What I need to do is get the car out of storage (May) and look at these things again. run these compression tests ect. I have a camera scope i can send in the sparkplug hole to take a peek as well.
Facing = Decking (some people say facing)

grannyknot: How fancy to meet you here as well! lol

 

Running good goes to my point, but I understand the -while I’m there might as well. There’s also curiosity and the - I want to rebuild a motor -feeling too.

Good luck and there’s always help here

[Av8ferg]

So the compression check will be a solid indication as to whether or not you need to do a total rebuild. If compression is good maybe just gaskets, seals and a head cleanup might be all you need. If compression is low then maybe “while you in there mentality makes sense”. Rings and bearings for sure.
My situation leads me to a total rebuild. I have 2 cylinders in the low 140’s. They should be around 170. I have a loose timing chain (stretch or the tensioner is bad.) I can hear it slapping the cover, and freeze plugs that leak due to corrosion. So I’ve decided to do the whole engine.
The other side of this coin is this. You have the engine out, all the accessories removed might as well go all out and get it all done. I can appreciate this approach. I don’t like unfinished work or unknowns.
If you have the time, I’d lean toward a total rebuild. The cost isn’t much more and you’ll learn a heck of a lot. As far as cams go. I’ve never been a big fan of turning a nice engine into a poorly idling engine that is just fast and not a great car to daily drive. I want a little more power but I don’t want to sacrifice a smooth running reliable engine either. They run best the way to were born minus a few minor things.
Consider finding a ZX engine with a P79 head, of just the head. You’ll get some extra power and not radically change the original design. I got my ZX engine for $400, with a warranty. Start looking at car-part.com for engines around you.
My 2 cents.


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[madkaw]

1 hour ago, Av8ferg said:

So the compression check will be a solid indication as to whether or not you need to do a total rebuild. If compression is good maybe just gaskets, seals and a head cleanup might be all you need. If compression is low then maybe “while you in there mentality makes sense”. Rings and bearings for sure.
My situation leads me to a total rebuild. I have 2 cylinders in the low 140’s. They should be around 170. I have a loose timing chain (stretch or the tensioner is bad.) I can hear it slapping the cover, and freeze plugs that leak due to corrosion. So I’ve decided to do the whole engine.
The other side of this coin is this. You have the engine out, all the accessories removed might as well go all out and get it all done. I can appreciate this approach. I don’t like unfinished work or unknowns.
If you have the time, I’d lean toward a total rebuild. The cost isn’t much more and you’ll learn a heck of a lot. As far as cams go. I’ve never been a big fan of turning a nice engine into a poorly idling engine that is just fast and not a great car to daily drive. I want a little more power but I don’t want to sacrifice a smooth running reliable engine either. They run best the way to were born minus a few minor things.
Consider finding a ZX engine with a P79 head, of just the head. You’ll get some extra power and not radically change the original design. I got my ZX engine for $400, with a warranty. Start looking at car-part.com for engines around you.
My 2 cents.


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I agree with all of this except the cam perception. It’s not the cam that makes for poor idle as much as the ability to tune. My 490/290 cam probably isles as good as a stock engine , but I have the ability to tune it. OEM EFI doesn’t allow tuning, but I think you can get away with some cam mods which do wonders for these motors . 

[Av8ferg]

I agree with all of this except the cam perception. It’s not the cam that makes for poor idle as much as the ability to tune. My 490/290 cam probably isles as good as a stock engine , but I have the ability to tune it. OEM EFI doesn’t allow tuning, but I think you can get away with some cam mods which do wonders for these motors . 

Madkaw,
What kind of EFI are you using? Sounds like he’s interested in a cam upgrade. I know a guy that had a black pearl 78 that put a performance cam in. He could never get it running smooth with EFI so he decided to switch to carbs and it was fast but it didn’t run as smooth as a stock engine.
Not sure if Cronoz78 wants to keep the car injected. TI would be nice to know all the additional mods to get an EFI engine running well with a cam upgrade. Like do you need bigger injectors, fuel pressure reg?? Not sure.


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[madkaw]

8 minutes ago, Av8ferg said:

 

Madkaw,
What kind of EFI are you using? Sounds like he’s interested in a cam upgrade. I know a guy that had a black pearl 78 that put a performance cam in. He could never get it running smooth with EFI so he decided to switch to carbs and it was fast but it didn’t run as smooth as a stock engine.
Not sure if Cronoz78 wants to keep the car injected. TI would be nice to know all the additional mods to get an EFI engine running well with a cam upgrade. Like do you need bigger injectors, fuel pressure reg?? Not sure.


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I am using megasquirt - so I have a distinct advantage to tune my EFI. But I have read of guys who have success with a tweak here and there and can run stock EFI with a bigger cam. The cam really wakes these motors up, but power is addicting. The stock motors (L28’s) are all in at 5000, so a cam does wonders. Since it’s been reported that the stock EFI does fudge on the rich side at wide open throttle, someone could get away with more power with the stock EFI.

Going carbs changes everything . 

Lots of info on EFI upgrades . EDI has come a long way

[siteunseen]

I think my $5 volume knob from Radio Shack wired into the coolant sensor wires would do the trick for a bigger cam.  I can flood it out now with it turned all the way clockwise.  I can't remember if it's a 1K pot or a 5K though.