L28 custom intake flange

[z-ya]

I might argue that, depending on where your 'at' right now. If you are currently injected and using an OE manifold, you'll notice power dropping off pretty seriously by 5500 rpm. The manifold is the leading contributor. Runners are *tiny*. Even on a bone stock L28, this manifold would wake up the top end. A couple 'gotcha's'... you will need some sort of programmable EMS as the factory L-jet would be 'lost'. Valves *will* float with stock springs. Right now, this motor, with a mild cam and matching springs, is pulling to 7300rpm... where its beginning to float valves. This manifold wants to spin! See where I'm going with this?... the issue will become one of mechanical limitations. If you address those, even on a stock cam and head, I believe there is plenty of room to justify a manifold upgrade.

Just my dos pesos.

 

Ron,

 

The latest motor I put together pulls strong right to 6500RPM. Cam is a 460/280 running 10:1CR. Stock valve springs. It makes almost 190WHP. No head work at all. Only running 25 deg total advance. The intake ports were opened up to match the N47 head. The TB port was matched for a smooth transition to the 60mm TB. The manifold is a late 280ZX (W42?) that has the plenum that is larger in the front, than in the rear. I'm curious to see how much of a difference this manifold will make. There is no way that it can add as much power as my "plank" coil mounting system (inside joke).

[Daeron]

I might argue that, depending on where your 'at' right now. If you are currently injected and using an OE manifold, you'll notice power dropping off pretty seriously by 5500 rpm. The manifold is the leading contributor. Runners are *tiny*. Even on a bone stock L28, this manifold would wake up the top end. A couple 'gotcha's'... you will need some sort of programmable EMS as the factory L-jet would be 'lost'. Valves *will* float with stock springs. Right now, this motor, with a mild cam and matching springs, is pulling to 7300rpm... where its beginning to float valves. This manifold wants to spin! See where I'm going with this?... the issue will become one of mechanical limitations. If you address those, even on a stock cam and head, I believe there is plenty of room to justify a manifold upgrade.

 

Just my dos pesos.

 

Ron,

 

The latest motor I put together pulls strong right to 6500RPM. Cam is a 460/280 running 10:1CR. Stock valve springs. It makes almost 190WHP. No head work at all. Only running 25 deg total advance. The intake ports were opened up to match the N47 head. The TB port was matched for a smooth transition to the 60mm TB. The manifold is a late 280ZX (W42?) that has the plenum that is larger in the front, than in the rear. I'm curious to see how much of a difference this manifold will make. There is no way that it can add as much power as my "plank" coil mounting system (inside joke).

 

 

I want to add that I, for one, would LOVE to see a dyno result on a stock or relatively stock NA L28, and a turbo i guess, while we are at it, versus the stock intake manifolds. I think that this manifold is the one to try as the first variable to see how much difference the manifold itself makes; so many of us have dropped larger injectors and put the 60MM TB onto an otherwise stock motor over the years, when all of my recent reading, learning, and growing is telling me that this manifold, with all other stock components (except maybe the TB) will PROBABLY make more of a difference than any of the rest. Curious to see what could be done with nothing but the mani and some larger injectors.

 

Hard data on this question would be FANTASTIC.. unfortunately, I am nowhere near even working on getting my Zcar running right now.

 

I just figured I would post to add a little more emphasis that this manifold setup may well be a good "first step" in tweaking your engine. SOME sort of induction work really MUST be done for any real performance anyhow.. 38mm intake runners just aren't enough!

[z-ya]

Curious to see what could be done with nothing but the mani and some larger injectors.

 

Injector size is not important, air-fuel ratio is. So as long as the AFR is around 13-13.5:1 for an NA motor, who cares how big the injectors are. Even the highest performance NA L-series only needs 36lb injectors. Going larger will just have a negative effect on your idle quality.

 

Hear is what I recommend for a modified NA L28 (stock fuel pressure):

 

- Stock CR, mild cam, headers, TB (140-160WHP): stock 18lb/hr

- 10:1 CR, medium cam, mild head work, headers, TB (160-200WHP): turbo 26lb/hr

- L31, 10:1, hot cam, head work, header, TB (200-260WHP): 36lb

[Daeron]

Injector size is not important, air-fuel ratio is. So as long as the AFR is around 13-13.5:1 for an NA motor, who cares how big the injectors are. Even the highest performance NA L-series only needs 36lb injectors. Going larger will just have a negative effect on your idle quality.

 

Hear is what I recommend for a modified NA L28 (stock fuel pressure):

 

- Stock CR, mild cam, headers, TB (140-160WHP): stock 18lb/hr

- 10:1 CR, medium cam, mild head work, headers, TB (160-200WHP): turbo 26lb/hr

- L31, 10:1, hot cam, head work, header, TB (200-260WHP): 36lb

 

Thanks for the clarification, but my intent in pointing towards "larger injectors" was merely as attempt to point towards another step to complement the manifold. I guess YOUR point is that, a mild cam is more complementary than non stock injectors.

 

Honestly, I just wanted to sound off in saying that IMO this manifold (or a similar one) is probably an IDEAL first step in modding an engine.. and I am curious to see what difference it makes by itself, unless a cam change is really needed to take full advantage of it.

 

Really, i was just trying to find a way to scale down the pipe-dream of dyno testing the difference made by any combination of ignition, fuel supply, and air supply that can be made with this type of free-flowing intake.. but of course if I REALLY wanted that data, I suppose I would need to do it myself.

 

Eagerly awaiting dyno results. thanks for pointing out the shortcomings of my previous post.

[Zmanco]

Hear is what I recommend for a modified NA L28 (stock fuel pressure):

 

- Stock CR, mild cam, headers, TB (140-160WHP): stock 18lb/hr

- 10:1 CR, medium cam, mild head work, headers, TB (160-200WHP): turbo 26lb/hr

- L31, 10:1, hot cam, head work, header, TB (200-260WHP): 36lb

I have most of the middle setup with the stock (1980) intake manifold. I did port match the intake manifold to the head (N42) and TB to the manifold, but other than that it's all stock. Cam is a regrind from Delta Cams spec'd as .480" lift with 284/284 degree duration and stock springs.

 

I'm still sorting out a problem with the LC1 O2 sensor, but once that's done I plan to dyno tune it. I'll post those results as a "baseline" if anyone is interested.

 

I follow Ron's thinking that the intake manifold is a significant limiting factor at this point. I had made myself a deal that once I got the FI set, that was as far as I was going to take this engine. In terms of "bang for my buck", I've been thinking that if I decide I need more HP, then I would consider V8 swaps. Seeing vids of those with LS1's makes me drool a little ...

[madkaw]

I personally like the pipe dream of dyno testing different engine components. Though I contributed to the wind tunnel testing with ernest, I would like more to donate towards renting a dyno for a day or so and try some myth busting of our own. I would think it would be feasable to an extent to try different components and their affects on horsepower and torque and see the printed results to share with the hybrid community.

Lets say taking a relatively stock l28 and trying headers and versus stock exhaust manifold. How about the difference in the SU manifolds, the n-36 myth. How about larger injectors and there effect. Of course the list is endless but so was the wind tunnel testing.

Just a thought!!!

[RTz]

Playing with numbers....

 

Bone stock L28e makes a devastating 48 Hp per liter.

 

Installing a Braap head, header and exhuast, re-tuning the L-Jet, while retaining the stock cam/stock intake, nets you loosely 68Hp/liter... for a 40% gain. Not bad. I've seen these very results time and again from a Braap head. Further, the LJet is still manageable becuase the torque curve, while higher, still has the same overall shape. The exception is at the top, where the 'brick wall' is now more defined. The intake manifold is done. 200hp is approaching the limit on an untouched OE EFI manifold.

 

For Rebello's hot street engines, again loosely speaking, 98+Hp/L is the norm... for an *additional* gain of 44%. This is with a serious cam, peekier, noisier, and harder on the valvtrain, coupled with a real induction system, and turning more RPM. This is a fairly nasty motor, whereas the first 40% feels like a refinement of stock... broad power and silky smooth.

 

Yeasterday I was talking to Rebello about a specific cam, and coincidentally, Dave had just finished up dyno testing a Braap head. I'm not at liberty to disclose the numbers but lets just say I commited to one about 5 minutes after I got off the phone. Which leads to.... In the end, its *still* about the head. The induction/exhaust and cam is what make it work. Its the woman that makes the dress, not the contrary.

 

Keeping it in perspective... at a whopping 48hp/L, almost anything has the pontential to improve the power.

 

What an aftermarket intake manifold will normally do for an L-series is allow the engine to breath at higher rpm. RPM is where HP lives. And if its a good manifold, it won't cost you much bottom end grunt... *that's* the tricky part.

[spacecase70]

I think you are definately on the right track, Ron and i would like to know what it would cost for a BRAAP head myself

[RTz]

SOME sort of induction work really MUST be done for any real performance anyhow.. 38mm intake runners just aren't enough!

 

Not picking on you but... if the OE manifolds had 38mm runners, this thread wouldn't exist. An N42's runners are under 32mm! The runnners shown in the above manifold are 1.5", or 38.1mm.

 

While I'm happy with the results, and its still way early in the game, I have no reason to go larger on a street duty motor.

[RTz]

The latest motor I put together pulls strong right to 6500RPM. Cam is a 460/280 running 10:1CR. Stock valve springs. It makes almost 190WHP. No head work at all.

 

Nice.

 

There is no way that it can add as much power as my "plank" coil mounting system (inside joke).

 

I can only imagine:biggrin: Have you posted pictures of it yet?

[Daeron]

Not picking on you but... if the OE manifolds had 38mm runners, this thread wouldn't exist. An N42's runners are under 32mm! The runnners shown in the above manifold are 1.5", or 38.1mm.

 

While I'm happy with the results, and its still way early in the game, I have no reason to go larger on a street duty motor.

 

sorry, it was a long and boring day. I obviously wasn't paying attention; I knew this but remembered it wrong.

 

These things happen when I have a whole day with nothing to do but internet; its a price I pay for owning and driving a subaru (which needs constant attention) while i dream, plan, and research for my Z. Now that I think on it, it is the main TB for my subaru SPFI thats 38mm (yes thats right it is THAT small) I plead temporary retardation, your honor.

[kj280z]

Hey all,

 

I've been reading the threads related to "additional HP" and possible gains that this manifold would provide.

 

I was present for testing that Rick Bowers did for James Thagard on his manifold. The manifold tested did not have velosity stacks nor did it have a shape designed to even the flow to number 6. I'm sure you guys have seen that manifols in this forum before.

 

Anyway, the testing proved that it was worth (From memory) around 24 hp over Ricks previous setup which was an N42 intake with 60mm TB (hogged out) and some port matching

 

Maybe Rick can clarify it for us...

 

Hope he sees this

 

Ken

[1 fast z]

Just thought I would throw this out there, is that I have 2 extra CNC'd intake flanges up for grabs. 225 a peice.

[RTz]

Anyway, the testing proved that it was worth (From memory) around 24 hp over Ricks previous setup which was an N42 intake with 60mm TB (hogged out) and some port matching

 

Ken,

 

Any more details... headwork, cam, exhaust, etc?

[kj280z]

Ken,

 

Any more details... headwork, cam, exhaust, etc?

 

Ron... Hey... Yes it had a TEP port and polish, with their turbo cam (it's a turbo motor) 3 inch mandrel exhaust and a "significantly worked" exhaust manifold.

 

The HP numbers were derived using data logs and showed some interesting results in many areas of the power band where the only addition was to add the new intake manifold... nothing else new was added... The same fuel and timing maps were used and they showed that there were significant "lean spots" with the addition of the new intake, thus requiring adjusting the maps to compensate for the increased "breathing"... Breathing = Lean "ranges" in the pwer band = more fuel required, meaning it made more power...

 

I am excited about assembling Justins manifold with the velocity stacks and "tuned" plenum because I believe it is a superior design to what was being tested.... Also, I now have the motor that all this testing was done on so I will be able to compare the thagard manifold to this newer design and give you some interesting feedback. When the testing was complete it was making 366 rwhp

 

Hope my explanation was clear... it's late and I'm deliriously tired...

 

Ken

[Guest znow white]

iam really curious to see some results as well as some flanges so i can get in on this thing

[JustinOlson]

For those that have dealt with machinists, sometimes they are very busy and it takes a little while for them to be able to dedicate time to projects such as this. I am trying my best to get a prototype flange in my hands very soon. I will keep everyone posted.

 

Justin

[JustinOlson]

We do have the possibility of having plenum extrusion machined like the attached pictures. This would make for a very affordable plenum with integrated velocity stacks.

 

[1 fast z]

I would put ALOT more radius inside those velocity stacks if I were you. Altease a .5" R. That looks like a .25r.

[v8dats]

looks great!