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Jason Moyle Racing
https://jasonmoyleracing.createaforum.com
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Return to: ROLLING ROAD & ENGINE DYNO RESULTS
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#Post#: 27--------------------------------------------------
Fast road MK1 rolling road results.
By: JMR Date: June 26, 2012, 6:47 pm
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To start the ball rolling, this should be of interest to those
who want the perk up their daily driver...
We had a fast road conversion to do recently in a Mk1 Cabrio.
The the guy wanted something he can go out on a sunny Sunday in
with the roof down and enjoy a bit of extra power when desired
but without the need to hit the redline everywhere.
I figured a conservative approach was needed so ported the head
in a different way to how I normally do them. I kept the valve
sizes at the std GTi 40/33, enlarged the throat area slightly
less than I would when looking for the best flow from the
standard size valves and left both the inlet & exhaust ports
totally stock/un-ported...no smoothing...nothing...just as they
come from the factory. The inlet manifold is also standard, as
is the throttle body.
Despite keeping the ports std, the increased throat bowl size &
valve re-shaping gave just over a 20% flow increase on the inlet
side from standard..I also made an interesting discovery with
the std hydraulic head flow...more on that in an article at a
later date.
I had the head skimmed to suit the cam I wanted to use, so
brought the chamber size down from the std 30cc to 27cc to give
a 10.5:1 C.R.
Being a later Cabrio it's a hydraulic DX with K-jet, so I fitted
a Newman Phase 2 fast road cam with 268 degree's duration & .420
thou lift & a vernier pulley.
Newman had a bit of bad press a couple of years ago with issues
of incorrect keyway locations on GTi championship supplied cams
etc, which was actually an error on the part of an outside
contractor, but as it say's Newman on the box...
Anyway, based on the quality & condition of a race cam I removed
from an old hillclimb engine, and the quality of the cams I've
since bought & the service received, we have become a Newman
dealer.
The owner fitted the head & cam to the standard 1800 bottom end
& timed it up as I recommended as a starting point...or at least
I hope he did!,,,along with a modded airbox, Jetex system, and a
tubular manifold. The manifold is a short primary...long
secondary type...virtually a copy of the std cast manifold &
downpipe...so I doubt there's much gain there.
And now excuse time!...
I did'nt get chance to make it to the dyno myself on the warm
Saturday morning (remember those!) when the Cabrio turned the
rollers, but with a conservative ignition timing of 27 degree's
running on 95 unleaded, a slightly leaner than ideal mixture
right through the rev range of 0.93 and no time to swing the cam
timing, the above spec made the power curve below...
[IMG]
http://i66.photobucket.com/albums/h278/mrhillclimber/2012-05-17133910.jpg[/img]
Peak power, as can be seen, hit 108hp at the wheels @ 5,500rpm,
and is hanging on very well at 6K still with 106...camshafts of
circa 270 degree's normally fall away fast after mid 5's so I
suspect the cam timing is'nt ideal for peak power in terms of
numbers, but when the whole curve was plotted up, both my dyno
man Alvin & the customer elected to leave well alone!
For comparison, on these rollers a std 1800 8v GTi makes 86hp at
the wheels & around 112-114ib/ft of torque when worked back, and
an 1800 KR 16v shows 110-112 at the wheels. With around 130ib/ft
now available from 2,500 to 5,500, and a peak of around
133-134ib/ft @ 5000, it goes up the road well enough...the smile
on the owners face after returning from a road test was enough
to convince my dyno man apparently!
As a package, it's mostly hit the target I wanted to
achieve...good road manners, no loss of low end power over
standard...in fact a bit of a gain, and decent urge up through
the rev range when needed. I think peak power numbers can be
raised with some cam timing adjustments as both the peak torque
& power points are a little high, and the leaner than ideal fuel
mixture could unlock another couple of hp going from previous
experience...though the owner reported back just over a week
after the rollers session to say how pleased he was overall, and
fuel consumption...or rather the lack of it... is better than
before...with twins about to enter the household the poor chap
needs all the help he can get!
#Post#: 72--------------------------------------------------
Re: Fast road MK1 rolling road results.
By: Stooza Date: July 9, 2012, 3:00 pm
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This offers great encouragement for my car ;D
#Post#: 82--------------------------------------------------
Re: Fast road MK1 rolling road results.
By: JMR Date: July 10, 2012, 3:12 pm
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;)
#Post#: 2239--------------------------------------------------
Re: Fast road MK1 rolling road results.
By: Gusaphinya Date: December 7, 2017, 2:58 am
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It is very good that I read this good. I like this content very
much.
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