Peugeot 205 1.9 with Kant cam and 38dgas carb
Discussion
Will it be possible to succesfully run a 1.6 8 valver with a weber 38 dgas carburettor and a Kent PT28 cam (race) 309/314 inlet/exhaust?
Anyone experience with a combination like this?
I have already fitted uprated valvesprings and spacers from puma.
Anyone experience with a combination like this?
I have already fitted uprated valvesprings and spacers from puma.
Edited by Keesjr on Friday 20th April 19:15
Thanks! The main jets were 135's and now there are 148's in it, the air correction jets were left stock, the fuel curve is okay now, a bit rich at low revs but around 12,5 - 13,0 everywhere else.
The carburettor is a brand new one, with no modifications.
As the chokes cannot be changed i'm leaving them alone and see how it runs at the track!
The carburettor is a brand new one, with no modifications.
As the chokes cannot be changed i'm leaving them alone and see how it runs at the track!
It runs okay, just need more power.
I have thought to fit a 4-barrel Holley 390 cfm carburettor, has anyone tried this on a four-cylinder?
Or maybe a big old carb from an old straight six BMW or Opel.
The head and cam are not restricting the enginepower, it just that this carb flows not really enough air for this engine.
Pumaracing? Any idea's??
I have thought to fit a 4-barrel Holley 390 cfm carburettor, has anyone tried this on a four-cylinder?
Or maybe a big old carb from an old straight six BMW or Opel.
The head and cam are not restricting the enginepower, it just that this carb flows not really enough air for this engine.
Pumaracing? Any idea's??
What's the difference between a DGAS and a DGAV? In my last post i said that the A/F ratio was between 12 and 13, but it leans out to 13.7/1 at 7500 rpm, so i'm going to fit smaller air correction jets to bring the ratio to 12.5 - 13.0/1 at 7500.
At the moment 185 air jets are fitted, so i'm to fit 175's and see what happens at the rolling road, maybe pick up some more top-end power too.
I also have been thinking about trying a spacer between the carb and the intake manifold, it almost always works on V-8's so it has to work on a 4-cilinder too, a 3/4 inch thick spacer fits nicely and the bonnet does still fit without hiiting the air filter, so i'm going to try that too.
Just making one modification at once and see what happens, if it works --> great! If it doesn't --> it was already as good as possible ;-)
At the moment 185 air jets are fitted, so i'm to fit 175's and see what happens at the rolling road, maybe pick up some more top-end power too.
I also have been thinking about trying a spacer between the carb and the intake manifold, it almost always works on V-8's so it has to work on a 4-cilinder too, a 3/4 inch thick spacer fits nicely and the bonnet does still fit without hiiting the air filter, so i'm going to try that too.
Just making one modification at once and see what happens, if it works --> great! If it doesn't --> it was already as good as possible ;-)
Thanks Oakdale, my engine also has a short inlat tract, a 1.6 carb manifold with a new carburettor mounting pad welded to it to mount the dgas in the right position.
When i'm going to the rolling road again we'll try your suggestions.
Is it so that the fuel drawn through the pump jets richen the midrange fuelling but leaves the top-end relatively lean?
Let's get the fuelling spot on then, and then further experiment with the spacer and some other little things.
Thanks!
When i'm going to the rolling road again we'll try your suggestions.
Is it so that the fuel drawn through the pump jets richen the midrange fuelling but leaves the top-end relatively lean?
Let's get the fuelling spot on then, and then further experiment with the spacer and some other little things.
Thanks!
So far i have blocked one of the accel jets and tried a couple of runs, but it hesitated because of not enough fuel, so both accel jets are back in place.
Got back to the 148 mains and 170 air jets instead of the 185 air jets, instead of starting to tail off at 6700/6800 it now pulls to 7200/7300 before tailing of, if needed it can be revved to 7800, then it seems to hit the wall and power stops immediately.
After that i fitted a 3/4" spacer between the manifold and carb, that also works, not much but it feel a little bit better from about 4000 onwards.
Can't wait to take it to the rolling road again to see the new power and torque curves.
I don't think the torque is much higher, but it feels like it's holding the torque till higher up in the revs, that's what is need a very long powerband!
Got back to the 148 mains and 170 air jets instead of the 185 air jets, instead of starting to tail off at 6700/6800 it now pulls to 7200/7300 before tailing of, if needed it can be revved to 7800, then it seems to hit the wall and power stops immediately.
After that i fitted a 3/4" spacer between the manifold and carb, that also works, not much but it feel a little bit better from about 4000 onwards.
Can't wait to take it to the rolling road again to see the new power and torque curves.
I don't think the torque is much higher, but it feels like it's holding the torque till higher up in the revs, that's what is need a very long powerband!
The modifications worked, it needed smaller main jets, and some adjustment of the ignition. It produces 162 Nm of torque / 5000 and 125 bhp / 6600 @ the wheels, by 7000 power drops off, it can be revved to 7500 but what's the point of that?
What next? I would like to try a 4 into 1 exhaust manifold, but i don't want to loose power lower (under 3500).
So does anyone know some dimensions for the right pipe diameters and lengths, or is that really something to try and see what happens.
On Dave Baker's site (pumaracing) he says that the stock cast iron manifold is already very good, and i'm convinced that this is really true, but if it's possible to gain another 5 to 10% of power and torque it's definitely worth the trouble to me.
Supersprint have an 4-2-1 manifold in their program and Magnex did or does a nice 4-1 version although expensive.
I'm not afraid of doing some work on a d-i-y manifold and like to experiment with different manifolds.
A bit like the Saab where Dave was involved with getting more and more power and torque from.
What next? I would like to try a 4 into 1 exhaust manifold, but i don't want to loose power lower (under 3500).
So does anyone know some dimensions for the right pipe diameters and lengths, or is that really something to try and see what happens.
On Dave Baker's site (pumaracing) he says that the stock cast iron manifold is already very good, and i'm convinced that this is really true, but if it's possible to gain another 5 to 10% of power and torque it's definitely worth the trouble to me.
Supersprint have an 4-2-1 manifold in their program and Magnex did or does a nice 4-1 version although expensive.
I'm not afraid of doing some work on a d-i-y manifold and like to experiment with different manifolds.
A bit like the Saab where Dave was involved with getting more and more power and torque from.
I'm going to weld up a manifold myself, in competition it always turns between 4000 and 7000 rpm, so my idea is that a 4-1 pipe should be okay and a little easier to bend and weld up, and also make more power, is there anyone who has experience with 4-1 and 4-2-1 pipes, because i don't want to loose torque at lower revs...
Thx for the tip to fit trumpets to my carb, i have some 45 mm ones on the workbench and they are short enough to fit under the air filter.
I'm also thinking to remove the cold-start choke valve, as i've never used it, it always starts with two strokes of the accelerator-pedal.
If the trumpets and removing the cold-start brings another couple of horsepower & torque i'm happier then ever :-)
So first see what the intake mods will do, then further with 4-1 or 4-2-1 pipes for even more power ;-)
I'm also thinking to remove the cold-start choke valve, as i've never used it, it always starts with two strokes of the accelerator-pedal.
If the trumpets and removing the cold-start brings another couple of horsepower & torque i'm happier then ever :-)
So first see what the intake mods will do, then further with 4-1 or 4-2-1 pipes for even more power ;-)
Hi, the trumpets i have here are 40 mm in height, going to fit them this evening and race them at the track (autograss) next saturday.
Should be getting close to 130-ish @ the wheels.
Next "development" will be the 4-1 or 4-2-1 pipe, although i'm biased to the 4-1 design, probably with a megaphone on it, that should bring in the torque a bit earlier and keep the power climbing longer, so maybe peaking @ 7000 instead of 6600 now.
I'll keep posting the results.
Should be getting close to 130-ish @ the wheels.
Next "development" will be the 4-1 or 4-2-1 pipe, although i'm biased to the 4-1 design, probably with a megaphone on it, that should bring in the torque a bit earlier and keep the power climbing longer, so maybe peaking @ 7000 instead of 6600 now.
I'll keep posting the results.
Then i may be better off with the stock manifold and downpipe and the 2 1/8" pipe i've fitted at the moment.
The "flow control" thing is in place now, so see what it does on the racetrack...
On the other hand IF it's possible to fabricate a 4-1 or 4-2-1 that looses no power down low AND gives even more on top that would be just awesome
The "flow control" thing is in place now, so see what it does on the racetrack...
On the other hand IF it's possible to fabricate a 4-1 or 4-2-1 that looses no power down low AND gives even more on top that would be just awesome
The home-made flow control thing is working good! It feels like it's making a bit more power and torque throughout the powerband, so i think it gained another 4-5 bhp or so :-)
For the time being i'm keeping the stock manifold and downpipe because the class regs don't allow tubular manifolds.
For the time being i'm keeping the stock manifold and downpipe because the class regs don't allow tubular manifolds.
Good news, it's too quick for the group i've been driving in so far this year, so i'm moving to a quicker class where it IS allowed to run tubular manifolds and more important double carbs :-)
I have a set of twin 45's in stock with manifold and everything to fit them, should be possible to get over 150 @ the wheels and lots of torque too.
I have a set of twin 45's in stock with manifold and everything to fit them, should be possible to get over 150 @ the wheels and lots of torque too.
The webers and intakemanifold are fitted now, it started first time and runs nice, next step is fitting some nice full-radius trumpets 45mm height and a big air filter, then it's back to the rolling road once more to check and change the jetting if needed.
And make a good heatshield to keep the hot air from the radiator away from the filter and carbs.
Hope to see 150+ bhp @ the wheels....
And make a good heatshield to keep the hot air from the radiator away from the filter and carbs.
Hope to see 150+ bhp @ the wheels....
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