L28 Stroker Build - I need your advice :-)

[madkaw]

I would go the same route as Diseazd. I'd use a p79 or p90 for your CR goals . It would be cheaper in the long run than sourcing 2mm HGs. It would also be a better chamber design to allow more timing .


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[german240]

I think you got me wrong - I want to use the N42 head as I don't have a differerent one available. 2 and 2.5mm HG are available from Kameari for around $200, so that's fine. All 90.5mm head gaskets are equally expensive

[Patcon]

On 12/29/2016 at 10:40 AM, german240 said:

Regarding the damper: I plan on buying this one. Thoughts?

Zcar depot has a good reputation but I have no experience with this damper. It may be overkill unless you plan on making lots of RPM's which gets hard to do with a stroker build

@Diseazd Maybe another build thread, I would love to see how you go about your build. A stroker build is on my "bucket list"

[Diseazd]

Definitely Charles.....This will be a total learning process for me. Eiji is going to talk me through it......I always like to do the actual building myself, but will source my parts from him. He has a machine shop that welds and restores the crank for even more stroke.....I think I'll settle for the LD stock stroke though. I just want to make sure that there are no clearance issues, and he has access to the Japanese thicker head gaskets to prevent any disasters. I agree with Conedodger that more CR is better and will shoot for 11 to 12 to 1. May need to burn a little race gas, but with enough Cam duration may be able to burn 93.....Eiji does. Can't wait to get started.....I'll follow this thread with interest german240! BTW, you need to check the big end rod clearance to the block.....you may or may not need to grind the block for clearance.......

Edited December 30, 2016 by Diseazd

[Diseazd]

http://www.oocities.org/inlinestroker/

Here's a site that may be helpful......This is the shaved P79 head I'll be using. German 240....Eiji uses the N42, so you'll be OK with your head. BTW, where did you source your KA24E pistons?

Edited December 30, 2016 by Diseazd

[moelk]

Don't forget that a good ignition system also makes the engine less sensitive to pinging.

Ad a Msd box to your zx dizzy and you will have a lot better spark.

Aim for just above a cr of 10 and you would be fine, not that important if it's a bit lower. It's better then have to back off the timing. 

You have access to good fuel in Germany,

Im right at cr 10 and i run 36 degrees advance. 

I use a E88 head with bigger valves like your N42.

We have 98 and 95 octane in the pumps here and it runs perfect on both.

 

 

 

[madkaw]

Doesn't seem like a very aggressive cam- why not bigger?


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[conedodger]

On 12/29/2016 at 10:06 AM, heyitsrama said:

 

That's why you wanna get good ignition system

 

 

On 12/29/2016 at 7:40 AM, german240 said:

I know - I just want to avoid to order several kits (they are $80 each). Maybe I can get away with the first try/guess 

I'll get the crankshaft rebuild (0.25mm shaved) and balanced. In Germany you get all kind of fuels: Regular (90 octane), Premium (93 octane) and "special" fuel but also from the gas station with 95 octane. All ratings (ROZ+MOZ)/2. 

Regarding the damper: I plan on buying this one. Thoughts?

 

Interesting. I heard that L series DON'T like compression at all  - that they are prone to pinging. Thanks guys!

We are talking about two different animals. Static compression is a calculation related to chamber volume and deck height. It's a number that while it may sound dramatic, is only a factor your starter has to overcome to get things moving. Dynamic compression is where the pinging might occur. Your cam overlap should take care of the excess compression. 

As has been mentioned, you'll want a good ignition system. I'm going with crank fired coil on plug. I would be very studious about selecting your cam. While it can be changed later, do you really want to? 

[Zed Head]

Compression ratio is almost a useless number without knowing the cam specs.  Cylinder pressure is what causes detonation, so higher pressures will lead to a higher likelihood of detonation.  But, due to the variation in gauges out there, the range of the numbers measured is huge.

In an ideal world, we'd all use calibrated identical pressure gauges and we'd talk about designing for a certain static cylinder pressure.  From that starting pressure you can get in to taking about dynamic changes.  CR alone doesn't tell you a whole lot though.  It tells you which way you're going but not where you ended up.

[heyitsrama]

6 hours ago, conedodger said:

 

We are talking about two different animals. Static compression is a calculation related to chamber volume and deck height. It's a number that while it may sound dramatic, is only a factor your starter has to overcome to get things moving. Dynamic compression is where the pinging might occur. Your cam overlap should take care of the excess compression. 

As has been mentioned, you'll want a good ignition system. I'm going with crank fired coil on plug. I would be very studious about selecting your cam. While it can be changed later, do you really want to? 

Could you post a picture of your ignition system if you have a chance? 

[german240]

17 hours ago, Diseazd said:

 I agree with Conedodger that more CR is better and will shoot for 11 to 12 to 1. May need to burn a little race gas, but with enough Cam duration may be able to burn 93.....Eiji does. Can't wait to get started.....I'll follow this thread with interest german240! BTW, you need to check the big end rod clearance to the block.....you may or may not need to grind the block for clearance.......

 

17 hours ago, Diseazd said:

..Eiji uses the N42, so you'll be OK with your head. BTW, where did you source your KA24E pistons?

@Diseazd Any idea what cam specs Eiji has in mind for your build? A CR of 12 sounds pretty agressive to me, especially with 93 octane fuel. However, good to know that Eiji uses the N42 head, too! I don't think I'll have clearance issues since I use the 8mm 240z rods (not the 9mm ones, but I got upgraded ARP bolts). I got the pistons from Rockauto, pretty cheap tbh (I think something around $180 for the set of cast ITM 89mm pistons). 

16 hours ago, moelk said:

Don't forget that a good ignition system also makes the engine less sensitive to pinging.

Ad a Msd box to your zx dizzy and you will have a lot better spark.

Aim for just above a cr of 10 and you would be fine, not that important if it's a bit lower. It's better then have to back off the timing. 

You have access to good fuel in Germany,

Im right at cr 10 and i run 36 degrees advance. 

I use a E88 head with bigger valves like your N42.

We have 98 and 95 octane in the pumps here and it runs perfect on both.

 

Maybe I could really go for 10.3 static compression. What cam are you using? BTW what is the advantage of a MSD box additionally to the ZX dizzy?

16 hours ago, madkaw said:

Doesn't seem like a very aggressive cam- why not bigger?
 

@madkaw I really want a fun street car with lots of torque. I think the cam I've chosen is neither mild nor super hot - somewhere inbetween (234deg@0.005"). I could go for more lift, however, then I'll loose torque at low engine speeds. Would you go hotter?

 

Thank you all - this turns out to be super helpful! I'm open to any suggestions or criticism

Tim

[conedodger]

You're still getting hung up on that number. When someone tells you 11.2:1 they're telling you static compression. Meaning the engine isn't running. Dynamic compression is the number you care about. There are a few of us here who have been around Z cars for decades that can impart experience but your next best move is to invest in a long distance phone call or email Dave Rebello. Be prepared to tell him everything you have and especially what your goal is. Ask him to sell you a cam. Dave has something like 30 grinds that he uses. He can set you on the right path. 

My ignition system is in pieces right now but here are the crank fire parts-