Jenvey vs. OER throttle bodies??

Larby

Club Member
I’m planning to be converting a 280Z to throttle bodies and wondered if anyone has experience of the OER setup?

It seems there’s a decent saving to be had compared to the Jenvey setup, by the time you’ve actually got all the required bits.

I’d be interested to hear the pros and cons of each if possible?
I’m aware of the issues with the Jenvey Heritage setup already.

A part of me wants to go with triple DCOE’s, but given that I have my own dyno centre etc, the extra benefits of ITB’s seems logical.

Cheers!
 

jonbills

Membership Secretary
Site Administrator
There's a decenter saving to be had using chinese ones :)
They're very simple devices. No need to pay carb prices for them.
 

jonbills

Membership Secretary
Site Administrator
Absolutely agree, got any good links? 😬
I got mine from the guy selling these.
I'm sure if you contact him he'll do a deal for a triple set.
I can PM you his email address if you like?
 

Larby

Club Member
I got mine from the guy selling these.
I'm sure if you contact him he'll do a deal for a triple set.
I can PM you his email address if you like?

Thanks, as it happens I had a better search last night and have emailed the manufacturer directly. I might buy a few sets and make up a couple of kits while I’m at it!
 

jonbills

Membership Secretary
Site Administrator
Thanks, as it happens I had a better search last night and have emailed the manufacturer directly. I might buy a few sets and make up a couple of kits while I’m at it!
Good idea - they'll also have 48 and 50s, if you went for one of them, I'd take a set.
 

Larby

Club Member
Good idea - they'll also have 48 and 50s, if you went for one of them, I'd take a set.
Good to know!
Any preference on size? I haven’t properly investigated that yet.
Generally I’d have said with ITB’s there’s no harm in going a bit big - you lose a touch of throttle modulation down low, but nothing too crazy. On that basis I’d be inclined to just go for 50’s
 

Robotsan

Club Member
There's a decenter saving to be had using chinese ones :)
They're very simple devices. No need to pay carb prices for them.
So is there a £ saving to be made with going down certain routes of converting an FI ITBs compared to say triple Webers or Dellortos?

Or is it kind of evened out by the need to add an ECU etc?
 

jonbills

Membership Secretary
Site Administrator
So is there a £ saving to be made with going down certain routes of converting an FI ITBs compared to say triple Webers or Dellortos?

Or is it kind of evened out by the need to add an ECU etc?
I think it depends on whether you want the comfort of branded kit and how much you can do yourself. Either way its hard to spend less than a couple of thousand.
Tuning modern EFI is much easier than carbs tho I have to say!
 

Larby

Club Member
So is there a £ saving to be made with going down certain routes of converting an FI ITBs compared to say triple Webers or Dellortos?

Or is it kind of evened out by the need to add an ECU etc?
I would have said, removing the cost of professional tuning, injection is always going to be more than carbs.

It’s probably not really fair to compare branded carbs like triple Webers to unbranded Chinese ITB’s, but even then.

I suspect that if you went full DIY, with a cheap manifold, Chinese ITBs, batch fire injection with something like a Speeduino or Microsquirt, it would be possible to put together injection for the price of triple carbs.

A big factor, as jonbills pointed out, is tuning.
If you factor in the sheer amount of dyno time needed to properly tune carbs, versus a day on the dyno tuning injection, suddenly costs balance out.

Injection will certainly be a far easier setup to live with too, better able to cope with being sat, weather changes and altitude changes.

For me, starting with a 280Z, staying with injection (but changing to ITB’s) seems logical.

I’m looking for a balance of price and quality. I don’t want to over-pay for a brand name (I’m actually a Jenvey agent and have used their products many times!) but likewise I won’t stoop to crap parts just to save money.

For the ECU, I’ll likely go mid-range, so MS3, basic Haltech, or ECU Master. I’m an agent for all three, so again, I’ll weigh a few things up.

I’d like to end up with a solution I could put together as a complete ‘ITB Conversion’ for the UK/EU market, complete with a base map. I suspect those who aren’t so confident would appreciate such a thing.
 

status

Well-Known Forum User
Question- why are you changing the fuelling system is it for bettter tuneing options
I’ve got Jenvys on mine had em for about 15 years once set up properly you don’t have to touch them,just had them re tuned to the new engine and they run nicely
 

Larby

Club Member
Question- why are you changing the fuelling system is it for bettter tuneing options
I’ve got Jenvys on mine had em for about 15 years once set up properly you don’t have to touch them,just had them re tuned to the new engine and they run nicely

Mainly because the car I’m buying is a non-runner due to a fuelling issue.
The Bosch system is somewhat antiquated and with time I’ll be building a higher performance motor to fit anyway.

Then there’s looks, sound, reliability, throttle response, the fact ITB’s are just awesome… 😬

For me, the stock Bosch injection system just doesn’t ‘suit’ the 280Z in my eyes.
I much prefer the look of carbs, so ITB’s are a nice middle ground and happen to also offer the best all-round performance.
 

Rob Gaskin

Treasurer
Staff member
Site Administrator
Good to know!
Any preference on size? I haven’t properly investigated that yet.
Generally I’d have said with ITB’s there’s no harm in going a bit big - you lose a touch of throttle modulation down low, but nothing too crazy. On that basis I’d be inclined to just go for 50’s
I'm completely out of my depth here but aren't 50s inappropriate for a standard 2.8?
 

Larby

Club Member
I'm completely out of my depth here but aren't 50s inappropriate for a standard 2.8?
I haven’t really investigated that yet, but it’s not as critical as with carbs.

Ideally, you want to size them so they flow a bit more than full engine flow (assuming WOT, full revs, 100% efficiency), so you get the best possible modulation across the throttle range.

If they’re oversized, the harm is that your throttle will feel very snappy and sudden down low - in extreme cases ‘full’ throttle will be reached by say 50% pedal, with even tiny pedal movements resulting in a large surge of power.

On the other end of the scale, if the bodies are too small, you’ll get lovely low end control, but they’ll restrict flow.

There’s more technicality to do with flow velocity, momentum of air etc etc, but that’s getting into ‘proper’ performance tuning and is a bit beyond me writing a little bit on here.

In all reality, I need to do some homework and establish what/which sizes are going to be best for L28’s, from mild to full 3L+ builds.

As a rule of thumb though, better to go a little bigger than risk being too small.
 

jonbills

Membership Secretary
Site Administrator
Jenvey have a handy table of expected power against throttle size. 45mm upto 270 bhp, 48mm upto 320 bhp etc. so realistically a std l28 doesn't even need 45s, but as @Larby points out, it doesn't hurt and gives you room for growth. who doesn't want more power?
 

Larby

Club Member
Jenvey have a handy table of expected power against throttle size. 45mm upto 270 bhp, 48mm upto 320 bhp etc. so realistically a std l28 doesn't even need 45s, but as @Larby points out, it doesn't hurt and gives you room for growth. who doesn't want more power?
Yep. Granted, 48/50mm may be rather OTT on a stock motor, but for someone like myself with bigger plans, it’ll be ok in the meanwhile.

If it had 500bhp stock, then having it that oversized would make it undriveable. The tiniest amount of throttle pedal would give you 100hp!

With a stock 150/200hp setup though, it’ll probably just feel really torquey.

The MK4 Golf R32 is an example I often use. It’s electronic throttle, obviously, but not mapped 1:1
At the start of the pedal travel, 10% pedal actually equals about 30% power, to make them feel really snappy and torquey.
Trouble is, the last 30% of pedal feels totally dead, as it only makes a tiny difference to blade angle.

It makes people with R32 golfs think they’re really quick, when actually the throttle is being artificially stamped on for them.

Also, what an awesome forum this is, that a quick question about a versus b throttle bodies has turned into an interesting and engaging discussion about throttle body tech!
 

status

Well-Known Forum User
Right I get that only I’ve drove a couple of 280 Zeds and ZXs and they drive nice but as you say if your going bigger,not sure wot my TBs are but are spot on to push my 3.2 so yeah good luck with that
 
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