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High Torque L28


Chewievette

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I'm trying to learn as much as I can about my ZX and potential performance before I start working on it this spring. But I'd like to know how I can get the most torque out of the L28. I originally planned to swap the motor for a sbc but The more I think about it the more I want to build up this straight six. I've been looking at all the performance stuff I can find but trying to connect the dots and knowing little to about these motors is, shall we say... difficult. I'm going to make a show car out of it so for one it has to look great and for two it has to get me to the shows!(and the occasional drag)

The one thing that I found so far that I absolutely LOVE are the triple weber carb setups but since I have a 1979 280ZX, it has fuel injection! So I started looking for Triple TBI setups and found one(link below), well acctually a few I talked to a few people about this particular setup and all said the same thing, since the injector is so far away from the cylinder, power will be non existant below 3K-3.5Krpm! with a Huge kick in the seat when you reach 4K. I like the huge kick part, but I'd rather have it at say...1,000rpm. So I did some looking and found a guy building a custom manifold that retains the stock location of the injectors but keeps the triple TBI. How much do you think making and using a similar manifold will bring the torque down?

I also looked at the Motorsport big bore stroker kit and I like the idea of it, however after doing some reading I dont think the 15% increase will be worth the $2,000! So are there any other options? I also read that most people bore the cyls out to 89mm but the MSA metal head gaskets have a bore of 91mm. Is it even possible to go that big with an L28? Does anyone make pistons that big?

As for the cams, I know there are literally a boat load of cams you can get for this engine but I havn't a clue how to know which I need for my setup. Can you guys give or point me in the direction of some tips for picking cams?

I'm also curious about turbo setups. I've gotten to know the basics and most everyone that's making decent power with this engine has a turbo so, I'd really like to know how much help I can expect from some boost.

I know I'm forgetting some crutial component right now ...if you know what it is, let me know. Please forgive me if I beating a long dead horse here, but every single thread I've read people are focusing on peak hp and totally ignoring the torque and horsepower curves ...1,200hp isn't going to do you any good if you cant use it!

Thanks.

 

Triple TBI:

http://www.racetep.com/ztripdcoe.html

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A few years back, I knew a guy here in San Diego (Kazumi) he use to work for the then Balboa Racing Team or BRT now Mossy Nissan in national city. These guys were taking out approx 10lbs from that L28 block and fitting them with Chevy Vega pistons. I could contact him and get exact numbers. I think it brought the displacement up to around 3150 or 3175?

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Guest bastaad525

As far as I know, anyone who builds an L28 for good low end grunt, uses SU carbs or EFI. The tripples have a pretty well known reputation for not making good power until higher in the RPM band.

 

Also remember, just about any upgrade cam you're going to find is going to have the same effect, moving the torque up into the RPM, and dropping torque at low RPM.

 

L28 Turbos make HUGE torque numbers. Take my example :) Bone stock motor, cam, pistons, stock EFI except for an upgraded pump and rising rate fuel pressure regulator, and intercooler, and upping the boost to about 14psi on the stock turbo. This combo made 300 ft lbs to the wheels! This is squarely up there with modern fuel injected chevy small blocks, just shy of what an LS1 Vette puts down. Talking stock of course :) Unfortunately HP was not nearly as close to the LS1 engine, but I could get it there with a bit more time, money and work. My exhaust is super restrictive 2.5" press bent, for one, and probably strangling a good bit of my top end power. But just goes to show what a mostly stock setup is capable of.

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Guest bigbadZ

I have a 77 280Z, never been on a dyno, but puts out enough low end torque to break 2 stock driveshafts, and the R200 rear end. Heres a list of mods to get there...MSA cool air intake, 83 280ZXT air flow meter housing with 280Z components (the Turbo housing is a bit larger) MSA 60MM throttle body, pre-smog intake ported for throttle body, ported and polished, gasket matched to head, head is decked and flat top pistons to raise compresion, MSA 6 into 2 header, 2.5 in mandrel bent exhaust, catco cat, turbomax muffler, 3 angle valve job, XR3000 ignition, PS91 coil, 8.5 MM plug wires, 1 stage colder plugs, MSD fuel pump, adjustible fuel press. reg., custom aluminum fuel rail (i forget where i got it) and i think thats it. Next will be the MSA stage 3 cam, which i have been building the engine for. This should be a good start for you, i am more then happy with the low end, and im hoping that the cam will help me out with top end, where i start to loose a little power. Also had a question for the parts finders...where can i get some larger fuel injectors? Im looking for 400-450cc injectors, i dont know if other prands are close to the bosch design, they all look a little difrent. Any help would be cool.

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Guest bastaad525

well as I said... your motor may make great down low power now, but with any hotter cam that will change. It will shift the torque band up ingo higher rpm, and you will lose some torque down low.

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A long time ago, (about 3 years) I actually did the swap from 2" SUs to triple dellortos (similar to webers). I had dyno plots before and after from the same dyno. I found I lost almost no low down torque, but gained about 5-8 % from 4000 I recall. I'll see if I can find the plots....

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Guest bigbadZ

BQR280Z, thanks for the info, i found the info on this sight (my bad for not serching around first) I guess theres actually a few diffrent injectors i can use on the car. I have a friend who found me 6 for 60.00 so im gonna go with that. And Bastaad525, i know it will change the power band, im hoping for it. I pull really well up to about 4,000 but it kinda dies off after that. I want that mid-top end power also, trying to get the best of both worlds. Anyone out there have pics of a moded fuel rail for the o-ring type fuel injectors? I have an aluminum fuel rail with barbed type brass fittings. I have an idea how it should look, but if someone out there has done the mod, please give me some info. Thanks all!

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I don't know what you want, as far as large tq numbers.

 

stock motor, and upgraded stock turbo, I put down 399ft/lbs @3500rpm.

Im hoping for 450wtq once I rebuild the engine I blew. :D

 

but it can be done.

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