Building A L28 (Na)

[TheCrazySwede]

Keep what you got and get a lighter flywheel for quicker response . Add that to triples and lower gears=fun!

Seriously - most folks wouldn't be able to discern the difference in these engines(rod/stroke ratio), but a lightened flywheel would be more evident.

Go over to Hybridz and look for at thread 200rwhp and street able

I'll probably end up going that route. The only other thing I wanted to change were the pistons. Are there any flat-top 86mm pistons I could use with the L28 rods?

[madkaw]

81-83 ZX flat tops

[TheCrazySwede]

The only flat tops I found were 86.1mm (ITM Brand)

Also, I won't have any problem with clearance switching to flat tops, right? Just want to take precautions...wouldn't want to hit the valves or anything.

[madkaw]

fun reading!

L6 heads; pics and descriptions - L-Series - HybridZ

L series dimensions - Stroke, Bore, Chamber cc's, etc - L-Series - HybridZ

Custom Cylinder head building.. Whatâ??s involvedâ?¦ - L-Series - HybridZ

[Jeff G 78]

200 crank HP isn't terribly hard to get with minimal cost. I built my race motor for about $1500 and it makes great power. I started with a F54/P79, but it would be about as easy to start with a N42/N42. Triple carbs are nice, but they are not needed to produce your power goals. 9.8:1 CR, a mild cam, and a good set of SU carbs will be all you need. I had my stock flywheel lightened. Make sure you replace your front pulley/harmonic balancer. Check with Dale Manufacturing to have them rebuild yours. I've seen many engines destroyed from failed dampers and a rebuilt one is not expensive.

[TheCrazySwede]

Thanks a lot for the links, madkaw!

200 crank HP isn't terribly hard to get with minimal cost. I built my race motor for about $1500 and it makes great power. I started with a F54/P79, but it would be about as easy to start with a N42/N42. Triple carbs are nice, but they are not needed to produce your power goals. 9.8:1 CR, a mild cam, and a good set of SU carbs will be all you need. I had my stock flywheel lightened. Make sure you replace your front pulley/harmonic balancer. Check with Dale Manufacturing to have them rebuild yours. I've seen many engines destroyed from failed dampers and a rebuilt one is not expensive.

Thanks for the input, Jeff!

Triple Carbs is something I want, rather than something I need. I already have a pair of SU carbs rebuilt by Rebello (Sold along with the motor when I bought it) so I'm already set in that area. TW's is something I'm going to get more down the line.

Thanks for the tip regarding the harmonic balancer! These are things I would like to know regarding the build...things that have been learned through experience. I appreciate you sharing your knowledge! I'll definitely keep that in mind, now.

I messaged someone from HybridZ who is very knowledgeable about L28's and their different builds, and he advised against getting flat-top pistons in an N42 head, and instead, told me to keep the dished ones. He told me that time and time again, he's seen the flat-top swaps done and have seen the effects of detonation in the head. The power gained from the extra compression is therefore lost due to the need to retard the timing. Since I'm keeping the stock valves and aren't planning on boring anything, I think I should heed his advise and keep the dished ones. As I mentioned, power isn't too much of a motivator. Reliability and responsiveness is what I want. A lighter flywheel is up there on the list!

Thanks a lot, again, for all of your help guys! It means a bunch.

[Jeff G 78]

Where do you live? The western part of the US doesn't have above 91 octane which limits your compression ratio. My street Z has 9.83:1 CR via flat top pistons and an N47 head and it runs great on 93 octane with no detonation. For my race motor, I went with the P79 head that is better to resist detonation just to be safe during long races as well as unknown gas near various race tracks. I shaved it to get to about 9.3:1 CR. I did not shim the towers and use longer valves, but rather just shaved and modified my chain guides and cam gear to get my chain slack and timing spot on.

[TheCrazySwede]

Where do you live? The western part of the US doesn't have above 91 octane which limits your compression ratio. My street Z has 9.83:1 CR via flat top pistons and an N47 head and it runs great on 93 octane with no detonation. For my race motor, I went with the P79 head that is better to resist detonation just to be safe during long races as well as unknown gas near various race tracks. I shaved it to get to about 9.3:1 CR. I did not shim the towers and use longer valves, but rather just shaved and modified my chain guides and cam gear to get my chain slack and timing spot on.

Hmm, that is a head scratcher. Given that this is my first build, perhaps it's better for me to be better safe than sorry, I suppose. Yeah, we only get 91 octane here in California (aka Commiefornia)...I've never used those octane boosters, so I don't even know if those things actually do anything. Back home (I'm from Sweden, in case that wasn't obvious, haha) we had up to 98 Octane at almost every gas station. That sure would be helpful over here!

What do you guys think? Is it worth it to go with the flat-tops? I was gonna call Dave Rebello and ask him what type of pistons they have (I know they have dished ones for N42 heads.) I was going to order my valvetrain upgrades from him anyway.

[TheCrazySwede]

So, I gave Rebello a call (Turns out they are about an 1 hour away from where I live!)

I asked him what type of pistons he recommends. He said he hasn't faced many issues with the flat-tops in the N42 head, but if a higher compression isn't needed, he would recommend the dished ones. I also asked him about valvetrain improvements, and he recommended a mild cam with a rather low lift (about .448) but he said that the Cam produces great torque and works great for street use. He said that Z Car Garage (Another highly rated Z specialty team) prefers that Cam Kit over most, mainly due to its power delivery.

I'm going to go over to Rebello (bring my head!) later this week, probably on Thursday, and see what can be done. They use ITM Pistons, by the way.

[Jeff G 78]

In Sweden you likely had 98 RON which is the same as our 93. In the US, we use the (RON + MON) / 2 method of calculating octane while Europe just uses RON. I have no idea why the methods are different, but the octane rating is actually about the same here and there.

I run a Web Racing #91 cam and I really like it. The engine pulls strong to 7,000 RPM. My cam is .450 lift and 280° duration. It was a new billet so I can run OE lash pads. I bought new rockers and lash pads, but I believe people have had good luck reconditioning the rockers at a much lower cost. I paid about $12 each for my rockers 20 years ago.

You can't go wrong with Rebello, but remember that speed costs money.

[TheCrazySwede]

I think you're right about the octane ratings.

Their Cam kit is around $290-300, which isn't bad.

I figure I'll go up there later this week and see what I'm in for. Ask any questions I might have an take it from there.

I'll let you know how it goes!

Cheers!

[TheCrazySwede]

Ok, so a quick update.

I dropped off my crank (w/ rods and pistons) and my block at a machine shop.

Crank just needs a polish, but the block needs to be bored.

So currently, I'm getting the block bored (0.020) and getting flat-top pistons to match. I figured I'd get the bottom end stable and ready before working on the head. Got new crank bearings, as well.