[onegearnofear]

hi guys i'm in need of some info im struggling to find, from the h20a to the h27a does the throttle body get bigger? or does anyone know of a replacement that will work on the h20a but need it to be bigger then 70mm, engine is starving for air above 3500 with the new tune...

[Gwagensteve]

Sounds like an excuse for the tune being too rich.

[Gwagensteve]

The H27 throttle body is apparently 60mm, H25 is apparently 55mm.

Be aware the late H27 as used in the JB grand vitara is drive by wire.

[vet 180]

Have run 300rwkws through a 60mm throttle. Seriously doubt that's your restriction

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[Gwagensteve]

I assume that was boosted though, and I also assume the H20 in question isn't.

[vet 180]

Gwagensteve wrote:

I assume that was boosted though, and I also assume the H20 in question isn't.

True. And yes i get tgat was compressed air going through that 60mm hole....

But do you see the H20 making enough power NA to warrent at 70mm throttle? You are going to need some serious revs and massive engine work to even get close. All i see a 70mm doing on a H20 is causing terrible drivabilty.

In saying that the OP seemed rather specific in his knowledge that the TB was the problem, so a little more info on the set up and why the TB isntge restriction would be interesting

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[onegearnofear]

ok so ive just had a heltec computer put in, the guy that tuned it said that above 3500rpm it was creating a vacumm and starving for air.

from my quick google searching i think the standard throttle body is 70mm i could be wrong?

other thing i was thinking if it isnt throttle body is it the manifold ???

do the h25a/h27a manifolds flow better???

i do have a sc 14 charger going on it once i figure out mounting but that could be some time away.

[onegearnofear]

is there any specific Suzuki engine tuners in Perth?

i got this work done at racing performance works in Osbourne park they are Mitsubishi tuners.

[Fatzook]

Id be surprised if there were any suzuki specific tuners ANYWHERE in Australia.

[Gwagensteve]

How much power is it making?

[onegearnofear]

Not a lot but I think gearing and tyre size could be a contributing factor.

How do I post photos I’ll put dyno sheet up

[vet 180]

onegearnofear wrote:

ok so ive just had a heltec computer put in, the guy that tuned it said that above 3500rpm it was creating a vacumm and starving for air.

from my quick google searching i think the standard throttle body is 70mm i could be wrong?

other thing i was thinking if it isnt throttle body is it the manifold ???

do the h25a/h27a manifolds flow better???

i do have a sc 14 charger going on it once i figure out mounting but that could be some time away.

Whats you current set up?

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[onegearnofear]

Engine itself is stock, extractors 2 1/4 cat back snorkel with k&n Pannel filter.

It pulled 110 hp 125lbft

Gearing hasn’t been changed to suit tyres yet so it still has 4.60 diff gears have 5:12 to go in when I get the time which I think will make a huge difference.

My knowledge of the engine starving for air is only that of which I was told by the tuner.

Looking to get as much out of it as I can before I supercharge it so I know that I’m in turn getting the most I can from charging it.

[onegearnofear]

Running 265/70/16 (30.7)

[vet 180]

onegearnofear wrote:

Engine itself is stock, extractors 2 1/4 cat back snorkel with k&n Pannel filter.

It pulled 110 hp 125lbft

Gearing hasn’t been changed to suit tyres yet so it still has 4.60 diff gears have 5:12 to go in when I get the time which I think will make a huge difference.

My knowledge of the engine starving for air is only that of which I was told by the tuner.

Looking to get as much out of it as I can before I supercharge it so I know that I’m in turn getting the most I can from charging it.

Ah ok. Your throttle body will be fine especially after you start sending pressurised air through it as mentioned earlier i have ran 300rwkws through a 60mm with forced induction.

If you engine is indeed starving for air as the tuner sudgests my first guess would be airbox and intake piping. Would have been good to get a run with it disconnected. I guess you can do that when you tune for the supercharger.

The H20a engine only makes around 140hp stock at the engine so you figures dont seem that far off considering drivetrain losses etc.

You are right in assuning the 5.12's will make a difference and they should.

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[onegearnofear]

That’s a good idea I’ll get a pod filter strap it to the throttle body see if it livens up any

Your right it would be close to stock tourque and power even with the terrible gearing, I can even hold 100kph in 5th now lol

I can be a bit of a stiffler for things being perfect so as soon as someone says it can be improved I’m on the ban wagon lol

All the small gains add up at the end of the day tho.

[onegearnofear]

Ok so after actually inspecting the throttle body I learnt two things

1. The throttle body is 50-55mm max

2. Some crazy Japanese man sat in his garage thinking of ways he could play with us westerners.

Had to take crossover pipe off to take the intake piping off which must be done in unison or it doesn’t come off or back on...

[atari4x4]

The ports on the crossover pipe got larger with every revision of the H series, I would match port the shit out of them on the h20a as they are tiny compared to the h27a

[onegearnofear]

I’m quite curious as to why the crossover is even there, from what I’ve read I’m guessing it has something to do with engine pulses which I don’t really understand but I think they got bigger because so did the displacement and the need for bigger plenum went hand in hand.

Once the charger go’s on I’ll take the crossover off all together.

[fordem]

I suggest a little more research before removing the cross-over - I believe the last generation of H27s have an electrically operated valve that opens & closes it - and when that valve fails it impacts performance negatively. What I don't know is if the failures were open or closed or exactly what aspect of the performance was affected, but it suggests that the cross over does serve a purpose, boosting either torque or power.

Of course this is on a naturally aspirated engine, forced induction might be different.

[Fatzook]

My twin turbo Nissan 300zx had one too. I think its common on V6 motors to equalise intake plenums. I dont recall reading anything about guys deleting them for performance reasons, which suggests to me that they were beneficial.

[vet 180]

The TB48 is a straight 6 but the plenum design separates out the back 3 and front 3 cyls with a butterfly valve in it that opens up at 3000rpm. A lot of guys mod it to stay open all the time.

Its quite a complicated system and a conventional intake would have been a lot cheaper to produce and a lot more simple without the chance of more screws falling into the engine

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[30ONA]

Isn't starving for air also called naturally aspirated?

[onegearnofear]

30ONA wrote:

Isn't starving for air also called naturally aspirated?

Well I suppose so but if I could get it running at its peak n/a the once I charge it I’ll be ahead even more

[Gwagensteve]

But peak N/A is peak what? Torque? Horespower? Maximum spread between peak torque and horsepower? HP/Litre? BSFC? If you're chasing peak horsepower it's going to be at the expense of torque and drivability. A mate years ago had a H20 and being the bloke he is he did ALL the research into H series power. There are apparently a race shop in Melbourne that had done a bunch of development on the H motor, and to get it to make power they were pulling over 8K rpm. Apparently the stock rods were still good for that (!) however, this engine was going in a clubman or something - i.e a very light car. That motor in a Vitara would be awful where the only thing that matters is torque to get a heavy car moving. Obviously for a circuit race car, drivability under the curve is irrelevant, but in a road car (and a 4WD) it's everything.

Peak torque is going to mean increased capacity, or retarded cam timing, small valves, high compression. you won't need a bigger throttle body to improve torque, it won't make any difference. IT"s all about maximum cylinder filling in the mid range, which requires high gas velocity.

I know this hasn't answered your question, but in all honesty, for the work you're going to put in trying to make a 100Kw H20 make 130Kw, you'd be miles ahead bolting in an XL-7 H27 with 141Kw, because it still has OEM drivability.

[vet 180]

onegearnofear wrote:

30ONA wrote:

Isn't starving for air also called naturally aspirated?

Well I suppose so but if I could get it running at its peak n/a the once I charge it I’ll be ahead even more

NA and forced fed has a different setbof rules. No piont optimizing an NA set up if planning to charge it later

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[onegearnofear]

Would optimising flow n/a not be benifisial once you add psi?

I’m of course looking for more tourque then peak power being a 4wd and also my work rig.

By at its peak I just ment solving as many henderances as I can, I know once you add psi the flow of the manifold/throttle body isn’t that much of an issue but if I was to rectify the flow issue before adding psi then would I not increase any gain I would get from adding psi?

I’ve chosen charging over turbo for more low down torque and instant power for 4wding.

Eventually I’ll probably get the 2.7L and then strap everything I’m working on now to it but that’s another 4K for recon engine I’d rather blow this one up first

[MrRocky]

More power for 4wding is not what the gv's lack. Id be more concerned about trying not to snap your cv's like toothpicks.
Sometimes the smoother transition to on power is better when your starting with a car that can push diveline reliability in standard form.

[vet 180]

onegearnofear wrote:

Would optimising flow n/a not be benifisial once you add psi?

I’m of course looking for more tourque then peak power being a 4wd and also my work rig.

By at its peak I just ment solving as many henderances as I can, I know once you add psi the flow of the manifold/throttle body isn’t that much of an issue but if I was to rectify the flow issue before adding psi then would I not increase any gain I would get from adding psi?

I’ve chosen charging over turbo for more low down torque and instant power for 4wding.

Eventually I’ll probably get the 2.7L and then strap everything I’m working on now to it but that’s another 4K for recon engine I’d rather blow this one up first

Short answer is no. Ill go into more detail later

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[Gwagensteve]

As Mr Rocky points out, everything downstream of the motor in a V6 Vitara is marginal with the H20. If being a "work rig" means high load/towing/lots of use/needs to be reliable, buy the right car for the job, don't try and build a small/light/urban vehicle to do that job. If (and it's a huge IF) you manage to build a reliable, drivable engine that makes significantly more torque than a stock H20, everything downstream is going to suffer, even more so if that adding torque means you carry more/tow more/drive harder.

If the outcome was something amusing for the sand or trying to scare SS commodores off the lights, more power to you - you know this is a short lived experiment for poos and giggles, but once you throw "work car" into the mix you're kidding yourself - get the right tool for the job. Building a higher horsepower/boosted H engine that has any semblance of reliability will cost more than swapping into a more capable work vehicle that doesn't need massive modification to do the job. What's the consequences if your work car is broken? What if you can't find a transfer case/crank quickly to keep it on the road? to say nothing of the increased load on the cooling system, oil temperature etc. You can push stock parts well beyond their design parameters for a little while and get away with it, but that's not the same as expecting them to do it for a prolonged period.

And the reason everything done for N/A performance isn't applicable for boost is because with N/A you're pulling the air into the engine via the vacuum created in the cylinder on the intake stroke. The maximum pressure differential is basically 1 bar. when you add boost, that goes out the window. you're now pushing air into the cylinder and cam profile, porting, intake manifold design, compression ratio - they're all different for boosted engines. One point about throttle body size - it sounds like you're intending a blow though throttle body using a remotely mounted supercharger (i.e not in the vee) so no, throttle body size will make very little, if any difference once boosted. (at the power levels you'll achieve)

If you ran a roots style blower with the throttle body before the blower (which is the common factory setup, Think LSA/LS9/L67, Mini Cooper S, and a whole bunch of other stuff) then you may well need a larger throttle body, because between the air filter and the inlet to the supercharger is where your vacuum and therefore restriction is.

Oh, as an aside, the Eunos 500 with the Miller cycle engine, ran, I think (could be wrong), a highly developed version of the H engine, with a factory supercharger. There's probably close to zero expertise about these engines anywhere, but they were torquey and reasonably powerful- the H engine being a Mazda design first used in the Eunos 30 and mazda 323 in 1.8 litre form.

None of which will save your driveline if you successfully make more power.