Which is better for the k series 52mm or 56mm throttle body

[420gazza]

after having this dispute on mg-rover.org i thought i'd ask the question on this forum and see what you're thoughts on this were

i've always swore by the 56mm throttle bodies on the k series and from past experience seem to work well from my point of view.

what do you lot think?


(lid on can of worms is opening slowly)

[BrackenFox]

*sits down with popcorn to watch the ensuing chaos*

This should almost be as good as a "Which end should you put the fuse when doing a battery to boot conversion" thread!

[420gazza]

*sits down with popcorn to watch the ensuing chaos*

This should almost be as good as a "Which end should you put the fuse when doing a battery to boot conversion" thread!

out of curiousity which end should you put.......

[ChrisD]

Probably 52mm, think 56 is oversized depending on what size engine. I don't see why rover would have designed a smaller tb if they could have just used the 56mm?

[Bobbybrown]

56mm all the way

[C2K]

52mm, Rover put it on the 160 for a reason.

It's part of the upgrade you need to get to 155ish on a standard VVC, and the 56 is overkill by a mile.

[Cableguy]

and the 56 is overkill by a mile.

Or by about 4mm

[stefaclese]

I'd say 52mm, might consider 56mm for higher output K series engines that have had a lot of work done on them, but tbh you get to a point where the inlet manifolds themselves are restrictive and you need to use ITB's, so imo 52mm is the best choice, and as said before, if the 56mm was better why would they create the 52mm?!

[C2K]

and the 56 is overkill by a mile.

Or by about 4mm

The drawing is scaled up.

[Cableguy]

and the 56 is overkill by a mile.

Or by about 4mm

The drawing is scaled up.

Damn i hate it when they do that, makes plotting the bastids awfuly difficult

[Punx0r]

Basically, don't fit a 56mm body to your car.
It killed torque on my 1.8K VVC, and transient throttle response was "interesting".
Basically made more power at 80% throttle than full throttle and was like an on-off switch.
Save your £30 and but a 52mm one...

That's what Grant said in another thread.

I'm guessing it'll come down to inlet air velocity?

[cas_uk]

Basically, don't fit a 56mm body to your car.

it made more power at 80% throttle than full throttle and was like an on-off switch.

That's what Grant said in another thread.

Ive experienced this also,so i can fully agree with it
It was on a 1.4 16v k.

[empsburna]

Basically, don't fit a 56mm body to your car.
It killed torque on my 1.8K VVC, and transient throttle response was "interesting".
Basically made more power at 80% throttle than full throttle and was like an on-off switch.
Save your £30 and but a 52mm one...

That's what Grant said in another thread.

I'm guessing it'll come down to inlet air velocity?

Would it be able to shove enough fuel in too?

[C2K]

Quite simply, what this guy says... goes:

The 56mm TB has been shown on the dyno to give less power than the 52mm, it is too big and gives it's best results when only 3/4 open.

Dave

End of discussion.

[420gazza]

how much of an improvement is the 52mm over the 56mm has anyone got any graphs to show as i'd be interested in seeing the difference

also some good points being made here keep it up

[Stu]

I'll try to dig out the RR graphs of them back to back on a VVC engine.

56mm one is better to about 2,000rpm, then the 52mm one has more torque.

At about 6,200 rpm the power drops off significantly on the 56mm one but the 52mm one goes to just before the limiter.

The 56mm one actually performed worse than a 48mm one at the top end.

[Grant620]

Deffo have results to back up that 56mm is worse than 48mm... Even though the 56mm did feel a wee bit better at part throttle.
52mm REALLY is the way forward.

[Ry_B]

Really does depend on which k series m8. On the 1.4 the 56mm is overkill imo.

[Stu]

Its the same for all 4 cylinder K series engines.

The VVC is the same as the 1.4.

None benefit from the 56mm throttle body.

[NoobCannon]

as i own bobbybrowns coupe now one of the first things i did was remove the 56mm TB as it bogs the car down when you floor it.

fitted a standard 1.6k TB, much better

imo the 56 is too big for a 1.6....

Steve

[< KEVIN >]

52mm, bigger doesn't alway mean better

[420gazza]

as i own bobbybrowns coupe now one of the first things i did was remove the 56mm TB as it bogs the car down when you floor it.

fitted a standard 1.6k TB, much better

imo the 56 is too big for a 1.6....

Steve

see i'm of a different opinion, when i put the throttle body on dans car i thought it made an improvement over the standard item as did dan.

whether or not the 52mm is better than the 56mm, i'd say the 56mm is deffo better than the 48mm plastic jobbie

[Bobbybrown]

as would I mate, maybe we should try a 52mm on the new coupe and see whats better

[Stu]

Rolling road tests of both back to back over the years have proven this is not the case.

I'd have thought this was pretty much the accepted situation by now.

Seat of the pants feels quicker arguments aren't going to dispute this fact IMO.

My VVC felt quicker when I decatted it. Rolling roads proved this was just a placebo effect as it sounded different. Hence the cat is back on the car. Other RR tests on 200's have backed this up with other cars over the years.

[420gazza]

some one got some RR graphs to show because as yet no-one's come up with any for me to look at