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Low power output - 1.6 twin cam
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Author:  marko [ Thu Nov 12, 2009 12:28 pm ]
Post subject:  Low power output - 1.6 twin cam

Hey Lads,

What HP at the wheels should be expected from a standard 1.6 + GTI head conversion?
I have a samurai running a 1.6 bottom end and mk1 gti head.
It runs an aftermarket ECU, 60mm sr20tb, matched inlet.
mk2 injectors, lift pump, surge tank, bosche 044 fuel pump,malpassi FPR, 2" exhaust.

It's been back for a dyno tune twice and It still hasn't made over 50kw(68hp) atw.
Compression check shows 170PSI across all cylinders with no variation. The engine blows no smoke and shows no visible signs of being in poor health.

However I am lost for words at the dismal performance on the dyno. Both standard engines should make more power than this, let alone this supposed "performance" hybrid.

I can understand the drivetrain losses associated with being a RWD vehicle, but surely it wouldn't be this much.
Could the larger wheel size (31") and gearing be affecting the numbers?

Any thoughts?

Author:  crazyman [ Thu Nov 12, 2009 12:32 pm ]
Post subject:  Re: Low power output - 1.6 twin cam

Cam timing off? :huh:

The intake cam has the dowel pin in the I slot on the cam sprocket and E for the exhaust sprocket? All the timing marks line up?

Another thing to look at is your fuel delivery. Remember that those injectors are from a 1.3. You could try 1.6 16v SOHC injectors, but you would have to retune. Not enough fuel and you would run great everywhere except under heavy load.

Author:  Mr.Pipe [ Thu Nov 12, 2009 1:01 pm ]
Post subject:  Re: Low power output - 1.6 twin cam

Is it a stock 1.3 GTI head? What ignition timing are you running? Have you tried advancing it ? Have you checked AFR with a wideband? Could you post your dyno curve? ...there could be clues in the curve.

Darcy

Author:  marko [ Fri Nov 13, 2009 2:34 am ]
Post subject:  Re: Low power output - 1.6 twin cam

I don't believe the cam timing is off. It was recently checked when a new timing belt was fitted.
Yes the head is stock. from a mk1 GTI.
I haven't personally altered the ignition timing. Previously it's been left in the hands of my tuner.
The vehicle has been on a dyno twice to have the tune looked at. However from memory the AFR was fairly rich, around 12:1.

I'll chase up a dyno printout to try and convey the results a little easier.


-Mark.

Author:  miniswift [ Mon Nov 16, 2009 6:46 am ]
Post subject:  Re: Low power output - 1.6 twin cam

Hi Mark,

Mk1 head is restricted compares to mk2 head.
I got Cultus service manual for mk1 ph2 which shows design changes from mk1 head.
Also, cam timing is different to mk2 engines.
Std mk1 Gti was 97ps and mk2 is 115ps.

Can you get hold of mk2 Gti head?

I know it's not much help.

Cheers
Atchi

Author:  marko [ Mon Nov 16, 2009 11:13 am ]
Post subject:  Re: Low power output - 1.6 twin cam

Hi Atchi,

I could fairly easily source and swap to a mk2 head, however I'm sure there is something more amiss with my setup.
ie: Currently I am achieving ~70hp with my 1.6 gti atw. Is the figure you quote of 97ps for the mk1 at the wheels, or flywheel?

If at the wheels, then by my calcs after adding the 1.6 bottom end I am producing ~25% less than the factory output of the 1.3 (It's late so correct me if im wrong here.)

Author:  miniswift [ Mon Nov 16, 2009 5:39 pm ]
Post subject:  Re: Low power output - 1.6 twin cam

Hi,

It is @flywheel.
I know what you mean by something else.
Someone told me that Swift gear box is very good and only loses 15% or something like that. So if it is 97ps it should give 82ps or 80bhp.

Are we sure it will increase performance by fitting Gti 16v DOHC head to 1.6?
Someone in know(may be Suprf1y) was saying ports are too small for 1.6!?

Can you not fir SOHC 16v head?


Cheers
Atchi

Author:  VR4 [ Mon Nov 16, 2009 7:13 pm ]
Post subject:  Re: Low power output - 1.6 twin cam

the 31" tires are for sure sucking some power out of it. 12:1 is also pretty rich for an NA engine. 170psi is pretty low compression for an NA engine. my 3000gt TT makes about 160 compression (8:1 ratio)


it seems you have a few issues contributing to your low power.

Author:  stevegti2 [ Tue Nov 17, 2009 3:54 am ]
Post subject:  Re: Low power output - 1.6 twin cam

with the 1.6 bottom end does it still have stock pistons aka vitara pistons as with the gti head this will make for very low compression around 7.4-1 [caarlo is the man for that one ]

steve

Author:  crazyman [ Wed Nov 18, 2009 5:37 am ]
Post subject:  Re: Low power output - 1.6 twin cam

What 1.6 bottom end? The 8v, or the 16v? That answers the compression question.

Author:  turbohull [ Thu Nov 19, 2009 10:29 am ]
Post subject:  Re: Low power output - 1.6 twin cam

keep in mind 1.6 pistons in a 1.6 (where they belong) gives a much higher CR than in a 1.3 because of the longer stroke.



31" tires, RWD tranny, transfer case, rear axle, they all add up. I'd like to see the curve from your dyno. a 1.6 w/GT head will give you plenty of torque, but it falls rapidly above 5500rpm, this could be why you see such low HP numbers.

Author:  stevegti2 [ Sat Dec 05, 2009 4:55 pm ]
Post subject:  Re: Low power output - 1.6 twin cam

fair enough there is more stroke lengh and comp will be higher than in a g13k but i cant see it being more than 9.5-10 does anyone know the compression ratio with this combo

steve

Author:  marko [ Sun Dec 13, 2009 4:25 pm ]
Post subject:  Re: Low power output - 1.6 twin cam

Having not done the initial conversion, I can't be sure of the engines internals.
However the engine number on the block denotes G16B.
Although all the peripherals (ie: power steer) are from the carby model.

Spent some more time on the dyno last week. Still only achieved just over the 60hp mark but did find a fair bit of torque in the peak driving rpm range.
The Afr's are spot on.

Also found the existing airbox/intake is producing quite a restriction, so it will soon be replaced.

Author:  stephennmm [ Tue Dec 15, 2009 7:22 pm ]
Post subject:  Re: Low power output - 1.6 twin cam

Find out what gear with those tires put you at a 1:1 gear ratio. Or put stock size tires on it when you will dyno it. I think that is why my numbers showwed low. I had a 3.78 final drive instead of the standard 4.10. Thanks Stephen

Author:  JooF [ Mon Nov 08, 2010 4:23 pm ]
Post subject:  Re: Low power output - 1.6 twin cam

Also keep in mind that your samurai is not a 1:1 transfer case... depending on year it could be 1.41 or 1.58, or even lower with some of the aftermarket gearing available. I really have no idea how they do the numbers up to calculate horsepower, but I suspect these numbers are just as important as your diff ratio.

Author:  marko [ Tue Nov 09, 2010 5:53 am ]
Post subject:  Re: Low power output - 1.6 twin cam

Interesting concept with the transfer case, as I do run substantial reduction gearing (1.7:1), 20% lower than the stock 1.409:1 high range.
Plus lower diff gears than most samurais. 4.09:1 compared to the common 3.7:1.
I always considered these reductions would be mostly offset by the larger tyres.

I had never considered the effect on final drive ratio, and hence HP/torque on the dyno.

Author:  LittleMSG [ Mon Dec 19, 2011 10:20 pm ]
Post subject:  Re: Low power output - 1.6 twin cam

Did you change the head to the newer gti style and fix your low compression yet? Even a stock SOHC 16v 1.6 should be around 190-200psi

Author:  marko [ Mon Dec 19, 2011 11:14 pm ]
Post subject:  Re: Low power output - 1.6 twin cam

Never bothered with a newer head.
The engine uses no oil, compression is identical across all cylinders. I believe there is no reason to believe this engine should have any higher compression. I've seen multiple references to low static compression with this conversion (8.6:1), This could coincide with results I am seeing.

Author:  DeTune [ Fri Dec 23, 2011 4:43 pm ]
Post subject:  Re: Low power output - 1.6 twin cam

with 170psi per cyl there is noway your compression is near the 10:1 gti CR unless you have in performance camshafts....

I suggest you start there. Get the compression up. Take out the vitara pistons and install some oversized GTi pistons or aftermarket pistons...Honda D16 pistons will fit into your standard 1.6L bore but you'll need to do some machining as the piston doesn't use a fully floating gudgeon pin. These should put you above the 10:1CR mark...

Author:  marko [ Fri Dec 23, 2011 5:39 pm ]
Post subject:  Re: Low power output - 1.6 twin cam

To recap:
With a bog stock g16b block and mk1 head with factory cams, the dynamic compression was only 170psi across all cylinders with a healthy engine. Rings seal well, no oil is consumed and the head has been recently reconditioned to ensure no valve leakage.
This seems to confirm people mentioning the 8.6:1 static compression that is a result of the hybrid engine.
Even after fitting 200/335, 210/340 cams, 60mm tb and a new tune 100hp couldn't be achieved.

Insteading of trying to raise the static compression, I went the forced induction route.

Author:  VR4 [ Sun Dec 25, 2011 2:30 am ]
Post subject:  Re: Low power output - 1.6 twin cam

Thats the way to roll with the low compression. Otherwise new pistons would have been required.

Sorry but stroke and cams have absolutely nothing to do with cr.

Author:  ng357 [ Thu Aug 20, 2015 3:44 pm ]
Post subject:  Re: Low power output - 1.6 twin cam

considering this conversion, does anyone know how much whp I should expect from the conversion with the stock 9:5:1 compression? My 1300 is currently doing 110whp... I am aiming to achieve 140whp there about, with forged rods as a future plan.

Thanks

Author:  marko [ Thu Aug 20, 2015 8:24 pm ]
Post subject:  Re: Low power output - 1.6 twin cam

Adding the 1.6 block will reduce the compression to less than your current 1.3 has.
I achieved 8.6:1 compression with mine, and at that level never achieved much greater peak power than the 1.3 was capable of.

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