building a hot street car

[AZGhost623]

This coming up summer in 2014 Im looking to tear down my engine and upgrade it. I have no idea how this previous builder built this engine, and so far I have found many shortcuts and other issues that I am not comfortable with. So I am going to rebuild it all.

 

My first phase is going to just pull the head, and send it off out of state for some head work by a respectable shop. Big Valve modification, with the 46/38 setup, port match and polish intakes and exhaust, along with the valve unshrouding and other stuff that goes along with this mod. I am told it will take 3-4 weeks so I can get it back and enjoy it on the car until phase two comes along. 

 

My second phase is going to be redoing the block in spring/summer next year. I have two ideas, and don’t know which would be the better way of doing things, so I am hoping for someone to chime in who knows better than I do. All pistons/rods will be forged, and light weight with ARP hardware. Being built to last!

1. My first thought is to reuse the OEM crank. Bore out the engine to 89mm, and use a short height piston with a pin height of 29, flat tops with valve pockets, and a long FJ20 type rod of 140mm correctly bushed. According to engine calculators this gets me a 1.77 rod/stroke. I realize this is a custom type piston, and a few people sell this type of setup. MLS Cometic gasket 1mm will be used as this setup is over deck by .65mm This seems to be a rare setup in my neck of the woods and none of my local Datsun clubs have info on this.
2. My second thought is to go normal stroker with the V07 crank which comes out to a 1.65 rod/stroke using the standard components with this kind of build.

Either way the crank either OEM or V07 will be balanced and lightened as well to work with whatever components I chose to go with. This will then tie into my EDIS system, lightweight flywheel and other mods I have already added from last year.

 

Obviously going the OEM route with the crank will be the more affordable route rather than trying to find a stroker crank. So running the long rod/short piston combo is more appealing to me to save on some costs, and get a better stroke. 

 

My questions are:

 

1. is there any benefit going the full stroker route over the long rod/short piston setup? What are the pro's cons?
2. can I upgrade my head now so it flows better, and make use of how my high compression setup is today without any adverse side effects?
3. Am I missing anything? My ultimate goal is a nice quick street car using the L28, I really like it a lot. I was hoping to do this in phases so I can save on the costs over time rather than one big dump of cash out of my pocket.

Thank you!

 

**EDIT** This will be non-aspirated, no turbos.

Edited October 30, 2013 by AZGhost623

[tooquick260]

Suggestion since planning to redo the head... buy another head. have that one rebuilt and then you could do the swap over the weekend and have less down time. I bought a P90 head for Cheap, had new valves, cleaned up port work and new regrind cam.

[AZGhost623]

Hmm i have looked for heads actually, but not very in depth. The ones I found were all rebuilt tho, so they wanted between 500-900$ for them. Its a good idea tho.

[tooquick260]

I did a search on car-parts.com

 

Found a pic n pay and they pulled the cylinder head off of the car me and shipped it. Head was $50 and $40 shipping. As long as the head has not dropped a valve you should be ok.

 

You probably will do new seats, guides, valves etc. New fly cut on the head you are ready to go!

[ctc]

Having built a stroker NA motor and spending some coin to do it, I will never do it again.  The time and money spent trying to get that last HP would have been better spent on gas driving the car.

 

My biggest issue, besides trying to sort bull from bologna, was the set up time required to finish the build. Multiple iterations of build up, measure, tear down, fly cut valves, assemble, measure again, tear down, clearance block for rod bolts.....etc.

 

For a street car, not intending to maximize hp for a given set of rules, my advise is to bend the rules.  Money in EMS or carb tuning, proper cooling mods, head work with a cam designed for it, blue printing the engine, stock or near stock (forged) bottom end, oil cooler, etc. will be money better spent.

 

Read up on all the finer details of a stoker build and ask if it is worth it to you for the few extra hp it will bring.  On the seat of your pants dyno, 50hp won't matter one way or the other.

 

Also, consider your driving style.  My engine had 50mm Mikunis, light flywheel, lumpy high lift cam, basically a full race prep.  Idle was 1200rpm, you either dumped the clutch at every light or stalled it, trying to even cruise to the burger joint became a pain.  Looked into EFI to see if I could tame it some and still keep the fun, ended up going L28ET.

 

For me, after dropping a bunch of money, doing that again just seemed foolish.  Couple tweaks here and there and I am back to the same power level, but much better on the street.

 

I know you don't want turbo, but my point is that a 200hp NA engine can sometimes be more fun than 300hp, at least on a daily basis.

[AZGhost623]

Bending the rules is what Im about =) This is why I am looking at the long rod/short piston setup. Its different and not the norm which makes it difficult finding info on it. It comes out considerably more affordable than a 3.1 stroker since you dont need to find the crank. You end up with a 3.0L using the stock crank with this kind of setup. The pricing isnt too bad since Ill be doing this in phases, its not that big of a hit that can be spread over the next 6 months compared to a single hit all at once would be tough.

 

Ill be sending my head off very soon, possibly next week to have the work done.

 

Oil cooler, EDIS, DCOE 152's, headers, shaved head, all that work was done last year in my initial build. My main issue is how the previous builder put this engine together, im not happy with his shortcuts I have found, and has actually caused me problems in the past. So I want to do it right so I actually know whats in my engine. Dyno tuning will also happen once I get my head back.

 

I am assuming more torque (atleast thats what the ozdat tool shows) with the long rod setup, but other than that, hopefully someone who has this kind of setup can chime in and provide some more information on how well it works, and holds up. It wont be a daily driver, and I definately dont want to have to dump it off the line every time, thats no fun. Part of the appeal to me is also the uniqueness of this setup since no one here in town (atleast from my local club postings) has this kind of setup too... Other than PMC alluding to he has run this 140mm rod setup and has had good success with it with his custom pistons, I cant really find anything else on it. 

 

I just want someone to elaborate as to what to expect with this kind of setup, and how well it works in a street car. 

[ctc]

I guess my opinion, having done the stroker route, is that the extra work and cost for custom rod/piston and crank combinations will not gain you anything on the street over stock rods and crank with custom pistons.

 

Based on the Oz calculator; Stock L28, 88mm pistions comes out 2.883L and 1.648 rod to stroke

 

From above 2.949L and 1.772 rod to stroke.

 

I just can't see where from a drivability/performance stand point you will feel the 0.066L of displacement and 0.124 increase in rod to stroke ratio.  If this were a track car, sure every thing you can do for a couple extra hp, great.

 

I just don't get it for a steet engine other to be able to say you did.

 

Now $$$ in head and cam work plus dyno tuning to dial it in.  That wound be money better spent than crank and rod work.

 

Edit:  if others can post quantitative evidence that given the same level of build and proper combination of compatable parts, that a 3.0L stroker has significantly more torque than a L28 given head and cam work dialed in for each engine.  I will humbally change my opinion, but I haven't seen the evidence yet. 

Edited October 31, 2013 by ctc

[Rob240z]

Rebello will offset grind a l28 crank for about $200. With the bore size you are planning that would put it right around 3 liters, maybe just over. If your already balancing the rotating assembly you might as we have it offset ground. $200 is cheap for the gain in displacement. 

[AZGhost623]

To me with these engines every little helps in getting HP out. Is it worth it? I guess thats all in the eye of the beholder right? I like to be different and have something unique. Is it worth it to spend $4000 on this kind of setup in parts, just to say I did? (cost so far for everything I want done with forged components, cast would be way cheaper)  Thats what Im trying to find answers on. Is it better to spend $2500 instead in getting the head all pimped out including the runners for a full race head? Just another variable to the mix I guess, but I have read many times here the power is unlocked once you get into that head with a professional who knows what they are doing, and I have no doubt. Thats why I have made it part of my process, to what extent I dont know yet.

 

I used the ozdat util, as well as. PMC has said he has great success dyno'ing different rod setups, and seems to have very good performance with the 140mm rods, and his custom pistons he gets from JE. This topic is what got me onto this kind of setup and started my research two weeks ago. http://forums.hybridz.org/topic/106806-long-rod-short-piston-combo-l28-tech-questions/?p=999382 I did reach out to JE about getting a set, but the data they need is way beyond my knowledge, so I reached out to PMC and working with Les now on possibly acquiring the parts (dont know what export costs from Australia is going to run) but he seems to be the man who knows this stuff for sure so goto the source. Of course they cant share customer data either unless they give me their super secret part number they create for their customer.

 

I would really like to hear from someone who has done a 3.0L setup and how well it performs/responds using all lightweight materials. I have heard multiple times lightweight material, and the longrod/short piston make for a great setup, not only in Z cars, but in any engine. Specifically what Im looking for is with this setup can you drive it around town easily? Can you drive to the track, have fun with it at the track for the day, and then drive home ok with it? One car to do it all? Thats what I would like. Again, the car wont be a DD, but will be out during the winter months (AZ Winters), maybe up the mountains, club drives, things like that. Also some occasional track days with NASA.

 

I am not familiar with the offset grind technique, so Ill have to go read up on that a bit. But if its 200$ while its out getting balanced & lightened, thats a no brainer.

Edited November 1, 2013 by AZGhost623

[Xnke]

I think you could do well to step back and take a look at what you've got, what you want, and what you really want to spend. You've got big plans and will need an enormous wallet to do what you're talking about unless you're doing a lot of the work yourself. And I don't mean assembly...I mean rod prep, head prep, engine assembly, carb work, exhaust, "a lot of the work".

 

First off, 46/38 valves are HUGE, and in my opinion have no place on a street L28 unless you're running 89 or 90mm bore diameter. I'd go so far as to say that with a proper valve job and really good valve unshrouding, 45/37 is big enough even for full-race applications. I was able to obtain flow numbers good enough for a 300HP 2.8L N/A engine  with the stock valve sizes, and any good L-series head-porter can do as well or better. Not all cylinder head castings are going to accept the big valves without undue stress...a little core shift one way or the other and you can run out of room for the exhaust valve. Talk to your cylinder head guy and get his opinions, get him to prep the chamber side first and make sure you can fit the big valves and not be shrouding them. A big shrouded valve is not going to flow as good as a stock size valve with good valve unshrouding done.

 

Second; you're planning for forged pistons and rods. Stock rods are forged, and are plenty strong enough...Don Devondorf ran prepped stock rods in his turbo L28 at 1000HP levels, switching to the Nissan sports option rods to save time and get the floating pin options with less work. Aftermarket forged rods aren't needed even for moderate race engines, good prepped stockers are just fine.

 

How much time are you planning to spend at 7000RPM+? If the answer is none...skip the forged pistons, good cast replacements are fine for any street engine that isn't exceeding the limits of the piston skirt/wrist pin section strength. A quality cast piston will hold up at 7000RPM, but if you are going to spin it, run with a forged piston. Any sustained engine operation above 7000RPM would benefit from forgings, but on a street car you'll need to balance that against the warm-up characteristics of forgings. Your comment about a long rod/short piston being better in any engine isn't really fully thought out...the shorter the piston, the shorter the life of the piston and the block bore. Going from a 130mm rod to a 140mm rod isn't going to mean much of anything in an engine that isn't living at 8000RPM for half it's life, and will be quite a lot of effort for little return in an engine that is street driven.

 

Stock crankshaft is forged. It can be lightened and balanced, high-speed balanced, ludicrous-speed balanced, to your heart's content. Knife-edging of the counterweights will save a little power above 7000RPM; but under that it's unclear if it makes a difference. Offset grinding of the crankshaft will change your rod length and compression height on your pistons...Make sure if you go that route that you are prepared for what will come.

 

If I was building a hot street N/A L28, then a stock stroke crank, lightened and balanced, with a lightweight steel flywheel that was balanced to the crank, doweled to the crank, and a quality damper up front would complete the crank work. Prepped and shot-peened stock rods would be next, with 9mm ARP rod bolts. Cast 87mm flat-top pistons would be acceptable for an F54 block, or 88mm flat-top forgings (can't find a casting I like available in that bore size yet) would be good for an N42 engine block. Quality rings and bearings, KA24E truck oil pump, and cleaning up of the front timing cover casting for ridges and flaws in the passages would complete the bulk of the bottom end work.

 

Cylinder head would be a P90 or P79 casting, skimmed a little to set the compression ratio after the chamber work to between 9 and 10 to 1. Camshaft selection would be determined by both the final port flow numbers and the compression ratio, bottom end being a 0.480" lift, 230*@0.050"  profile on a 108 lobe center, up to a 0.530" lift, 270*@0.050" profile cut on a 106 lobe center. It would depend on how the ports flowed...if I need more lift to get the flow I want, bigger cam profile...if I can get it with less lift, well, that's less work to do with springs, valves, and valve seals. Bigger cams will want more RPM to make more power.

 

What size are your carbs? DCOE's are great...but if they're 40mm throttles, you'll be limited to around 7000RPM. 45's would make more power, and more RPM. Spend the time and money for good carb tuning, and run an air filter.

 

Ignition system...if you're running at 7000RPM and under, the dizzy is ok. I'd go with a crank-triggered system personally, but it isn't really needed till your engine is living between 5000 and 8000RPM, and even then some people get along fine with the distributor.

 

You will want a 3" exhaust with a good header. Primary size, 38mm is good up to 250-275HP, 42mm for anything higher. Secondary size 2.5".  Set the throat diameter of your final merge at about 2.25", then cone up to 3" and out the back.

Edited November 2, 2013 by Xnke

[AZGhost623]

Great info Xnke! Thanks for taking the time to write that all out, Ill buy you lunch the next time Im in KY

 

I am using a respectable Datsun shop over in California who has been doing this for years, and is a little more affordable than Rebello. They will be doing all the machine work and purchased a ton of my stuff through him last year. I hoped to do this in phases. Get the head work done first, and then next spring do the rest of it. I budgeted about $4500 for this setup not overly expensive IMO... That includes pistons/rods forged, required headwork, and balancing the rotating assembly. Everything else is already on the car. I will be putting it together. I was planning on shipping my head out this week, but now Im not too sure after your comments.

 

Already got the 2.5" Exhaust, 10# flywheel, Headers, Edis, DCOE 152's, P90 with .080's shaved off, Crower 480/280 @ .050 with 106 lobe center CAM, and Schneider valve train components, oil cooler, and big aluminum radiator. What I know about the block, it has flat top ITM pistons that are oversized +1mm (.040). Dont know anything else. So I figured Ill just take care of all that while its all out. That way I know everything thats going on in my engine and I know its done right.

 

I know I have read many times, balancing the rotating assembly gives you great performance along with windage or scraper components. Ive always been under the impression that everything needs to be sized appropriately hence the big valve mod for what I was trying to accomplish. But if I am to stay with what I got, and just get the head work done, 45/37 (+1mm) is what your recommending? Im all up for saving $$$ if I am going down the wrong path here.

 

I am curious as to why your saying the engine will have a half life with a short piston/long rod combo. Can you provide any insight as to why that would be? Flushing this kind of money down the tubes just to do it all over again in 3-5 years is not what I was looking for. Car is registered as a classic so maybe 1-2k miles a year.. those will be 1-2k fun miles tho, around 7000 rpm mark heh...

 

You sure about the oil pump? I always heard the F54 turbo oil pump was the best flowing one out there? 

Edited November 2, 2013 by AZGhost623

[Tony D]

The two different setups will require different cam grinds.

The bigger bore will unshroud the valves, which you will want for higher rpm breathing.

 

I'd stick with a stock stroke, or offset ground crank, forged pistons (simply because with ITB's and the right cam, you won't be able to help yourself going over 7,500 with ease and the cast stuff just won't hold up: BANG!) With forged pistons you can wing the hell out of it and not just think "will this be the one that breaks them and makes the engine sound like ice cubes in a blender when it comes back down to idle?" With EFI. Our Bonneville Engine wouldn't idle below 1,700 on 45 DCOE's, on TEC2 and TWM ITB's it idles reliably and smoothly at 900rpm with a 15# total-weight Tilton Flywheel/Clutch Assembly. With a heavier combination like the 11# Flywheel and standard clutch cover (total weight 35# total weight) it would be streetable I think. ITB's may get by with 40mm bores, but there is no drivability issues with 45's and the flow above 7,000 is considerable (we picked up 40 HP at 8200 rpms....look at Monzster's L24 Build for his 'hot street engine' which was not constrained by racing class rules. And ran a single throttle body to boot!)

 

Crankfire ignition, without reservation. Come into the modern age. Spark scatter at high rpm kills engines. Even hot street engines.

 

Big Valves are big money and with what they flow out of stock valves nowdays you don't really need them. JeffP used larger valves on his first head build, now has standard ones flowing just as much!

 

It all depends where you send your head to get the work done.

 

"Don Devondorf ran prepped stock rods in his turbo L28 at 1000HP levels"

No, he did not. But for this build, lightened prepped stockers will be fine.

 

The block wear is a moot issue using the N42 Casting, don't detonate and the piston skirts will stick around for quite a while as well. The forged piston engine will use more oil... pffft! I have gone over those economics countless times before won't revisit them here.

 

The L-Engine  and KA engine use the same oil pump. It's why they're still available from Nissan for our cars. Gasket is the same also. Thank you Parts Department Counter Dude from El Cajon Nissan for that bit of Nissan/Datsun Trivia!

 

Put your 2.5" exhaust on E-Bay and get a real one. 2.5" is marginal for STOCK engines, it's too small for high rpm bored out versions. Period!

Similarly for the DCOE's, if I read it right, they are 40's and while you can use them.....they will limit the engine useful range.

 

The power in a small engine comes from RPM's no two ways about it. Stock Stroke and 8,000 or a stroker with a power peak at 6500 or thereabouts. Look at the system, not the parts.

[Xnke]

One of the few things you can read from the Honsowetz book without having to glean from a photo...talking about how Devondorf was running stock rods and switched to the "currently unavailable" sports option rods to save prep time. Backed up in the other publication that was recently posted here, as well. Heck, there are L24e small-journal rods being flung around on offset ground LD cranks pushing 8000RPM out there too. (One of them is local to me, and while we've not convinced him to dyno it and see where he's at, 12.4@111mph is good enough for me.) Stock prepped rods are perfectly fine for 99% of applications with this engine.

 

I have been caught drooling over the investment cast alloy rods from Merchart...568 grams...138mm...NCA...

 

I was looking into the long rod/short piston configurations, and it just doesn't seem like good money spent when you get the pin height that short.

 

I'd get your headwork done, find out where your head will take you (220cfm intake flow at 28" *can* net you 300FWHP) then decide on the rest of your configuration.

 

(I know what you mean about the 2.5" exhaust Tony, I'm slowly aquiring parts to replace mine!)

[ctc]

I was looking into the long rod/short piston configurations, and it just doesn't seem like good money spent when you get the pin height that short.

 

I'd get your headwork done, find out where your head will take you (220cfm intake flow at 28" *can* net you 300FWHP) then decide on the rest of your configuration.

 

 

+1

 

This was the point I was trying to get across.  Head work on stock bottom end, then see what you need.

[Tony D]

Go back and re-read that again. You will clearly see they STARTED with prepped stock rods and quit at 100 HP a hole. 

The San Diego Article backs THAT up as well.

 

They did NOT use the prepped stock rods on the 1000+HP Engines. And that's not read from somewhere, that's straight from Don and his Engine Builder both.

 

For N/A setups, sure. Not for 700+ Turbo Cars.

 

I can tell you for a FACT that L20B Rods on an L20A Crank twist just fine well over a mere 8,000 rpms.

 

See my youtube video if you want to hear what it sounds like. 1st Gear Shift light was 9,500, subsequent shift lights were 9,300, and while testing for valve stability the engine went considerably higher than that.

 

Prepped Stock Rods.

 

But that engine wasn't making 100+ HP/Hole!

 

As for the head, the flow and what lift it flows at makes a difference, and you HAVE to solidify the big bore / short stroke or smaller bore / longer stroke combination as the cam events will be different as will the acceleration rates of the cam ramps.

 

(Another thing to glean from the San Diego Devendorf Article was the assymetric cam---not just the basic assymetry, but the  ramp assymetry. THAT was what Ron was talking about in his re-engineering of the cams back then.)

[johnc]

And set aside 25% of your engine build budget for post build tuning.  Most folks forget that tuning is where you get that last bit of horsepower, not in the build.  If you budget $4000 for a build, reduce that budget to $3000 and set aside the $1000 for dyno tuning and parts swapping to make the engine work.  You'll end up with more power then the guy who spends $4,000 on the build and has no money for tuning.

[AZGhost623]

If going to a longrod/short piston is futile in the sense it really doesnt offer much of a performance gain, Ill stick with what I got in the block today and get it all balanced. Im in agreement that headwork is the most important piece in unlocking flow.

 

Ill reach out to Steve Nelson next week at TEP, and tell him about the changes I want done on the head. Ill go with +1mm oversized valves which seem to be found easily, and make sure he opens up the rest of the head as discussed. While the head is off and gone for 3-4 weeks, Ill pull the block and have the internals balanced with the flywheel at a shop here in town.

 

I already have two hours of credit time with a dyno shop here in town. Since the car is carb'd I have to supply parts/jets and things since they dont have access to these weber parts. My plan will be to get it close here at home, then buy a few sizes of air correctors and main jets to tune in the high rpm side at the dyno shop.

 

I appreciate all the great responses, and knowledge that has been shared. Thanks guys!

Edited November 3, 2013 by AZGhost623

[Xnke]

I would seriously reconsider Top End Performance, myself.

 

I've had dealings in both Datsun parts and Mitsubishi parts with him...neither went well or smoothly, nor did I get what I paid for.

 

That's all I've got to say on that front.

 

Anyway, I'd really reconsider on the +1 valve sizes...they're just not needed in 99% of applications and can actually HURT performance in some cases.

[AZGhost623]

Other than Rebello, who else can do this kind of work? I did reach out to Braap, but he is unavailable until summer/spring next year. Betamotorsports website seems to have disappeared as well. There isn't anyone I would trust in Arizona to do this right unfortunately. Only had 1 problem with TEP last year with my DCOE's he just sold them to me stock as is rather than jetting them like he said he would do for my setup. But other than that it was fine working with him.

Edited November 3, 2013 by AZGhost623

[Lazeum]

You should build your engine to your goal with parts matching each other. It goes with head work, cam choice, comp ratio, etc.

I had this experience with Braap who knows what he's taking about. Everything has been setup as a whole project. I wanted torque for a fun street machine, This is what I've got now and I'm very pleased with the result.

 

People around me are asking why I did not put forged internals, why I did not put this & that in my engine, why I did not balanced the whole assembly, the pistons to 0.1g, etc.. My answer is always the same: "it was not needed for an engine with power band from 2500 to 6000 rpm"

 

If Braap is not available, you could try Bryan Blake (1 fast Z) who's also doing some head work. He's almost local to you, he's in Phoenix, he should be able to help you also with your combo.

His website: bandmzcars.com