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Installed TWM induction and Programmable EFI with Pics


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I’ve seen a few posts recently on the pros/cons of converting to FI and benefits of a TWM set-up. I don’t get a chance to contribute as much as I would like to this forum due to lack of time (usually working on my Z) but I wanted to write a few words on my latest adventure.

 

Engine:

What you see in the pictures is a L28, N47 head, flat tops, 1mm gasket, 490†cam, and mild/medium porting. This is NOT a street car. It sees Solo and Open track. My goal is a very quick Z running on pump gas ($).

 

Air:

Attached is an old Cannon intake with 3 x 50mm TWM throttle bodies. Attached to them are 6 K&N filters. I had to port out the intake to match the head on one side and the TB’s on the other. It was a huge amount of aluminum to remove. The intake is much lighter now. Those 50mm TB’s are huge. It works great for me but I don’t recommend for a street car. They’re like an on/off switch. I terrorize people in the pits trying to get to the track. I can cruise in 5th gear at 55, and the TB’s are barely cracked off idle so my computer wants to lean it out. In addition, there is very little vacuum to speak of so forget using a MAP for tuning. I chose the K&N’s as an economical solution to filtration. They were made for Kinsler style FI and have a tapered bell for mounting on straight tubing. I ordered and cut aluminum tubing that fit the TB’s and the filters perfect.

 

Fuel:

Injectors are from a 75 Mercedes 450 SEL, barb style, about 40lb/hour. I custom machined a Holley fuel rail blank to give the barb injectors an O-ring seal. I have a drawing if anyone wants to duplicate. It will work with stock ones also. 3/8†Aeroquip hoses deliver and all originates at an ATL fuel cell. I have a large body BMW Bosch pump and an adjustable regulator.

 

Management:

Fuel is controlled by SDS with TPS load sensing. I chose SDS for $ and built in programmer. I am very happy with it. I had to use an Innovate LM-1 to get it tuned right.

 

Overall:

Again, my car is a track car and rides on a trailer so I didn’t make many compromises. I converted from a very trick setup based on stock components. I’m happy with the TWM set-up. It looks and sounds awesome, even better than Webbers. But, I believe the gains are marginal compared to a well-ported 75’ manifold and one large TB. Again, 50mm would be way too large for a street car but works great for me. The SDS is great and I can’t say enough about programmable EFI. I haven’t dyno’d yet, but I put this engine around 225-250 hp at the crank. It had to be driven back to Orlando from the Reynolds, GA Hybrid event and got 21 mpg, BEFORE I tuned it with the LM-1. It has power and correct mixture under most all loads and speeds. Webbers are always a compromise and look at the cost of tuning them if you think that is the way you want to go.

 

Future:

The next engine will be some sort of stroker with higher compression. I built this induction system to grow into anything I might conjure up in my normally aspirated dreams.

 

If anyone is attempting to try something similar, let me know and I can try to steer you away from any mistakes I made.

 

Clark

 

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That's some nice work there. :-D

 

I do have a couple of comments...

 

First - you are right - the ITB setups don't pull very much vacuum. However, if you sum the vacuum signals from all of the cylinders together, you will get a much better signal than your current setup does, especially at low rpm. It should be good enough to use a MAP sensor with - several others use this setup with success. Even if you decide to continue using TPS mapping, this setup will still give you much better vacuum to your brake booster.

 

Second - what are you using for a fuel pressure regulator? It doesn't look like you are pressure referencing it (the only vacuum signal I see is going to the brake booster). This is apparently not an issue for you currently, as your system appears to be working. However, not pressure referencing the FPR severely limits the dynamic range of your fuel injectors - you will have the largest pressure drop across the injectors at idle, forcing you to use artifically low injector pulsewidths, and the pressure drop across the injectors will be at it's lowest at WOT, where you need it most. Additionally, not using a pressure reference will tend to give you inconsistent results, as a given injector pulsewidth will deliver different amounts of fuel depending on the engine's load.

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The Cannon manifold you are using has the crossover tube, so just hook up the booster port to your brake booster, and you should be OK. Depending on the cam you are running, you may need some sort of vacuum storage (cannister).

 

BTW, I built the same engine (N47/flat tops), except that it has a stock cam with just a 3 angle valve job. The other difference is that I used a NA 280ZX manifold, and I ported to match the head gasket, and the 60mm TB. I'm also using a stock 280ZX distributor, with the timing set to 8deg BTC. It has what looks like the same header you are running. It also has a 2.5" exhaust with a Supertrapp.

 

I'm using a Megasquirt, with MAP and VE table load sensing. The TPS is just for enrichment. It is putting 164HP to the wheels. Power starts dropping off over 5500RPM, so more head work and a more agressive cam would help. I'm using the stock 19lb/hr injectors. They peaked at 95% DC on the dyno. I have a set of turbo injectors I may put in it next season. The car is a track only 240Z. 20MPG on the track. See this thread for the dyno plot:

 

http://hybridz.org/nuke/index.php?name=PNphpBB2&file=viewtopic&t=34186

 

Pete

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The Cannon manifold you are using has the crossover tube, so just hook up the booster port to your brake booster, and you should be OK. Depending on the cam you are running, you may need some sort of vacuum storage (cannister).

 

Oops - missed the crossover... :oops:

 

The regulator comments still apply, though...

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TimZ,

 

I ageree with you on thre regulator as far as the lack of a vacuum reference. Although I have seen an ITS 280Z use a non-mnaifold reference regulator.

 

Another comment on the fuel system, shouldn't it be connected like this?

 

Pump => fuel rail => regulator => return to tank

 

Pete

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"However, if you sum the vacuum signals from all of the cylinders together, you will get a much better signal than your current setup does, especially at low rpm. "

 

I had all the vac signals tied into a chamber when I first started tuning. It gave me a little boost to about 10"HG at idle, and around 13" at low speed. It was not enough for the SDS MAP tuning after 2 months of trying. When I switched to TPS it fell right in with about 30 minutes of driving. For track use and even most street driving, the TPS load sensing works surprisingly good.

 

I could hook the vac system back up for brake boosting but I haven't had much of a problem since I idle at 1300RPM and yes the runners have the x-over tube to equalize.

 

 

"the only vacuum signal I see is going to the brake booster"

 

There is another vacuum line running to the FPR

 

 

" shouldn't it be connected like this? Pump => fuel rail => regulator => return to tank"

 

It is connected like this???

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I did the Electromotive/TWM setup on my 510 about 7 years ago. I built a L22 with headwork, cam, etc, etc. The reason you can't recommend it for a street car is the size of the TBs, just as you stated. I went with dual 48s and really wanted something closer to 42-44mm, but they were on back order and I didn't want to wait. Anyway, I had a little of the same problem, where the throttle was sensitive off idle. I'd highly recommend the setup, but going with the low 40mm units instead. They'll flow more than enough for any L series, considering most run Mikuni or Weber 44/45, respectively with 38mm chokes, so the unrestricted 42s would still flow more and the throttle response would be much better. Anyway, there's my 2 cents. More on that car at:

http://www.dimequarterly.tierranet.com/articles/readers_dime_2_3.html

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Looks awesome!

 

I suppose since the Cannon manifold has a "crossover", the crossover is sizeable enough to be thought of as a method of sharing carbs between cylinders (i.e., like a plenum manifold), or not, like a true independent runner manifold? The crossover passage OD is small, so I'm thinking it's more like an IR setup?

 

IR or not has a huge effect on what size carbs/TBs to use. If IR, you need alot of carb/throttle body bore area.

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The Cannon manifold seems to act more like independent runners. 6 little engines if you will. Although the cross-over tube has a rather large id, >1/4", each runner "pulses" vacuum with valve lift. The only way to get a steady vacuum reading is to run all 6 together into a small manifold (1/2 id tubing, 1-2' long, minimum).

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clarkespeed wrote:

It is connected like this???

 

So does this mean that the fuel system is plumbed this way? Sorry, it's hard to tell from the pictures. It's also hard to see the manifold line going to the FPR.

 

Nice job BTW :-D !

 

Pete

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Wow, those ITB's are big.

On the Bonneville car we were running a bigger cam and with only 45mm TWM bodies the terminal HP ended up in the 290's to the rear wheels at 8300rpm or thereabouts.

 

Which was 55hp more than 45mm Webers. The choice was 55mm Webers or 45 TWMs and with the costs, we decided to go EFI. Thing idles at 800rpm and started on a 39 degree F morning at the Lake like nothing was out of the ordinary. Nothing like EFI!

 

Man, I like those Air Cleaners... :shock:

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I had actually bought a set of 40mm Webers and when I priced getting them tuned I backed off and sold them on e-bay. I knew they would be marginal for my engine, I think they had the 36mm chokes. I knew if I went with the TWM/FI set up, I could build any engine I wanted underneath and push button tuning is free.

 

Did I mention my induction noise is louder than my exhaust? Very pleasing to the ear.

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