Jenvey Individual throttle Bodies

[N61WP]

Jenvey Fuel Injection Throttle Bodies for motorsport

Some times I can get myself worked up and talk myself into projects whether they make $$$ sense or not.
I have about decided to buy a set of the short Jenvey Throttle bodies to fit my dual DCOE manifolds and run them with a Mega Squirt ECU. To remind everyone of my odyssey with my GT...I have a very warm 2.0 with 11:1 and a TGSI racing head, large valves, wild cam, etc, border line streetable. I have been running it on a SSD 45 DCOE...I have never been able to get it to run great down low...trust me, I have tried every jet/e-tube/choke combo known to man. All the Weber experts tell me you have to have 2 carbs with a beast like this, so this is what I planned to do, but I still can't get past cutting the sheet metal to get them to fit. Here's where the Jenvey throttle bodies come in, they are about 1-1/2" long, leaving lot's of room. I also know that too short of a intake tract can also hurt low end performance, but I feel that the 5" Cannon manifolds are long enough. With the Mega Squirt I should be able to adjust out low end drivability issues. I plan to start with it just controlling fuel until I get all the bugs out, then hook it up controlling ignition in the future.

What I can't seem to get a handle on is sizing. I know they don't have to be as large as carbs due to not having venturis. Using Jenvey's engine specs by HP per cylinder, I would only need 38mm TB's. I know that smaller adds to the low end response, but going too small hurts top end. The US distributor suggested 45 or 48's, but I'm leaning towards splitting the difference and going with 42's. Any Ideas about sizing? Thoughts on the whole project?

Jc

[namba209]

Ask yourself these questions, what RPM range will most of your driving be in? Redline all the time or something a lot less. What do you want for power, top end, botttom end or, mid-range. How much air will each one flow and what is the max airflow will each cylinder handle. RallyBob knows much more about this than I but, with intake pulses the same applies as with exhaust pulses, some where in the RPM range, the incoming charge will push the previous charge into the cylinder, packing it into the combustion chamber. The same applies with the exhaust, where the previous pulse will extract the current one out the cylinder. Lots of things to consider, but the prime shoud be, where do you want the power to begin.

[tomking]

If you do it and want to sell your SSD 45DCOE let me know. Thanks.

[madhatterpdc]

This is an upgrade that I have always considered. The two pieces that I am missing to get this done are cash and an engine worthy. EFI through individual throttle bodies is simply stunning in appearance and performance. If you are wondering what others will think, go to the Factory Five forums and run a search on "stack injection", which is what the V8 crowd calls this setup, although proper stack injection systems were mechanical, but I digress.

Anyways, *my perception* (meaning I have not installed and run an ITB setup, but after researching the topic) is that an EFI system including O2 sensors, will do a much better job at maintaining proper A/F ratios at lower RPM's which translates to smoother idles, better throttle response, MPG, power, etc. It's the equivalent of changing emulsion tubes at a rate of several times per second.

Now, in a DSD or SSD carbureted environment, we choose choke sizes according to what will offer the best venturi effect over the widest range of RPM's, we often wind up choosing a choke that is a little smaller in order to preserve idle and low rpm performance. Now, if all else is equal, and we switch to EFI, we should consider that the computer will work out the low RPM mixtures, allowing us to use a slightly larger "choke", thereby gaining high RPM flow, with little sacrfice to low RPM mixtures and idle quality.

Best of luck, I'll be watching closely.

[RallyBob]

Originally Posted by N61WP What I can't seem to get a handle on is sizing. I know they don't have to be as large as carbs due to not having venturis. Using Jenvey's engine specs by HP per cylinder, I would only need 38mm TB's. I know that smaller adds to the low end response, but going too small hurts top end. The US distributor suggested 45 or 48's, but I'm leaning towards splitting the difference and going with 42's. Any Ideas about sizing? Thoughts on the whole project?

Application is the word of the day. If you want low rpm response and strong midrange for autocross...go with the smaller size (38 mm). It will flow comparably to a 45 DCOE with a 38 mm choke...and that is huge for a 2.0 unless it's for racing use! You'll retain more flexibility and response with the EFI vs. carbs anyway.

In Europe (Sweden anyway), the rally guys like 45 mm TB's on 2.0 litre CIH engines, but that is for a 225-230 hp engine, which spends it's entire life between 4500-8500 rpms. A friend of mine there dyno tested one engine, first with 45 DCOE/40 mm chokes, and then with straight 45 mm TB's and EFI. The carbs had better power from 2500-4500 surprisingly, but the EFI won out everywhere else...better idle, better response, better top end power, and more peak power (from 221 to 227 hp, no other changes).

If you are running open track events, you might like the top end of the 45's better, but straight 38's still flow enough for 200+ hp. I'd only worry about the really big stuff if you are twisting it super high and don't care about power below 5000. I'm going to run four 52 mm TB's (actually two GM Tuned Port EFI 'twins' since the bore spacing matches the 2.2 head better) on my Bonneville engine for example, but I intend to shift at about 10,200 and make peak power at 9500-9700 rpms. So size it for your intended use!

Bob

[N61WP]

Well, I have pulled the trigger...don't anyone tell my wife, she's still waiting on new countertops! I ordered the throttle bodies last week and the complete MegaSquirt II with sensors and wiring tonight. Next, I need to order the injectors, fuel pump, filters and new lines.

Here's my latest question: The dealer I ordered the ITB's from told me that on some of the new cars they are not using a return line. The fuel pump has a regulator built in and it just bypasses internally within the pump. Has anyone heard of this? Is this too new to be an option? It would save plumbing a 2nd line.

More to come,
Jc

[namba209]

I've heard of something similar, except instead of a pressure regulator, the computer supplies a variable voltage to the pump to either increase or decrease the volume and pressure. Wierd folks these computer programmers and bean counters. Just think, that's another fuel line they don't have to purchase and install. .

[RallyBob]

Originally Posted by N61WP The dealer I ordered the ITB's from told me that on some of the new cars they are not using a return line. The fuel pump has a regulator built in and it just bypasses internally within the pump. Has anyone heard of this? Is this too new to be an option? It would save plumbing a 2nd line.

Better price them out, a lot of the new cars with returnless pumps have a price tag approaching $600 for a replacement pump. They are usually engineered for each application too. In the world of turbo upgrades, etc, it is usually cheaper to plumb an aftermarket pump and a return line than to source a returnless high-po fuel pump!

[hrcollinsjr]

Originally Posted by N61WP ...told me that on some of the new cars they are not using a return line. The fuel pump has a regulator built in and it just bypasses internally within the pump. Has anyone heard of this? Is this too new to be an option? It would save plumbing a 2nd line.Jc

I have 2 '96 model V8 Dodge PU's that don't use a return line.

Harold

[davegt27]

sports injection






Toyo 20V TB






HTH
davegt27

[wrench459]

Any updates on the project Jc?
It seems I'm following in your foot steps ie hate to cutup sheet metal to get a good flowing intake. Bob made a point I've not thought of before..using a tune port throttle body,but in my case a lot less radical.
Question I have is where to place the injectors?
In the TB or closer to the head.

[N61WP]

So many wires, so little time.....

This is uncharted territory for an old shade tree like me.

James

[N61WP]

After 2-1/2 years apart, I now have a running (not quite driving) Opel GT with Jenvey ITB controlled by MegaSquirt II, ver. 2.890. It starts right up and idles at under 1000 rpm, even with my crazy cam. I still need to work on the fuel tables as it don't want to take the throttle without bogging. I can't take a chance as I have 11.5:1 compression and need to stay on the rich side to be safe. I am using a wide band sensor that can help me tune it.

It still boggles my mind how many variables there are to be inputted into MegaTune or TunerStudios. I am reading and playing on the computer until my eyes blur, but I still think I'll need a kid from the Play Station Generation to get it really tuned right.

Thanks to Markandson who helped me get it running by posting his original setting.

I'll begin to post pictures as soon as I can get a break from work.

James

[wrench459]

shade tree James
NOT
Way to go the rascal runs and idles.
First thing I would do is go into the spark tables and remove 4 degrees timing.
Before any hard runs!
Then log the actual vs commanded A/F ratio and make the appropriate adjustments.
I like to use the step method.

You think the megasquirt has tables look at the throttle by wire in the late model cars.

Keep up the good work James!!

[RallyBob]

Dan is correct, even with a big cam, with 11.5:1 compression you won't need or want as much total timing as a normal Opel.

I'd start at around 15° BTDC at idle, and not go over 26°-28° for starters...at least not until you have the fueling close to being dialed in.

[N61WP]

I have been researching local tuners and have found a shop w/Dyno that should be able to dial it all in. I'll be in and out of town for business the next few weeks, so it may be about 3 weeks away. Until then, I intend to start over with a new tuning file using Jeff's numbers. I can't seem to find what I screwed up in my saved files, so it's beter to start over.

Thanks for the timing advice.....I will definitely drop a few total degrees as the computer shows 36 and my light showed 34.
I have took a few pictures that I will show and explain my madness...

James

[N61WP]

These pics show how I routed the fuel from the low pressure Carter pump in the back to the larger fuel filter w/return line in the nose of the car. The line then comes up to the right radiator support where I mounted the high pressure fuel pump. Fuel is the routed up to the front of the fuel rail.

[N61WP]

The return fuel is routed from the back of the fuel rail, through the regulator at the front of the engine and then back to the return line on the fuel filter.
I used the longest air horns that would fit. The rear most horn is actually the same Length, but instead of the filter mounting on the it's lip, I pushed it all the way in and sealed it with rubber weatherstripping. My throttle cable pulls down from the bottom, using the same setup I had on the SSD Weber.

[N61WP]

All the wiring came through the footwell by the trans tunnel and runs under the side carpet just under the lip of the console to under the rear cover, coming out at the end of the console. I was going to cut a hole in the metal to run them through, but then decided to only cut a notch out of the plywood of the deck. Even though a little will be exposed you really won't be able to see them. In all my games with this car, I have avoided cutting it up. Maybe one day someone will want to put it back all stock and that will be doable. I ran all the wires through flex looms for protection and took the time to solder and heat shrink all connections to try to avoid problems later. I have the Megasguirt relay box mounted in the low section under the deck and the ECU mounted above on the plywood deck where the spare tire would go. The wire from the relay box and vacuum line go up and behind the MegaSquirt and are well protected. This way, to hook it up to a laptop only requires popping the snaps on the vinyl flap...no tools required.

[davegt27]

Very nice setup

Davegt27

[hrcollinsjr]

Originally Posted by davegt27 Very nice setup Davegt27

Neat and well thought out!

Harold

[SantaClaw]

I'm using a multi throttle set from Dbilas in my GT: dbilas dynamic




There is a similair kit for the CIH

Works great, and includes everything you need, there's even an air collector if you want a turbo\stock fuel injection.