i think the dyno curves are more a reflection of the intake manifolds (runner length) than the carburetor type. of course, they are related as the carbs are specific to the manifolds. Although, as an experiment, the SUs could be adapted to the Edelbrock manifold. The Edelbrock manifold exhibits the typical short runner dyno curve. I agree that the SU set up is better for heavy car, automatic transmission use. In a light-weight car (Morgan for example), the 4-barrel type manifold would be better.
Thanks for these videos. I'm seeing very different use cases here for manual and automatic cars. With my auto i hardly ever use more than 3,500rpm and it's clearly spent much over 4,000rpm. I can imagine as standard, the manual is a little bit dull (it's basically a diesel!) and a cam and 4 barrel if nothing else will make it more fun to rev out. But it's clear as most P6s are autos, people need to stop and think because it's easy to make the car worse for general driving with conventional tuning. I'm seeing the 3.9/4.0 as a sweet spot for a build. I'd like to go for a hotwire setup on 4 hole injectors, because I really like the drivability of EFi and I know how to program the 14CUX.
I think 3.9/4.0 is a good choice, I recently dyno’d one, it was tired and literally had bugger all oil pressure but still churned out more power than most 3.5 along with tons more torque
Hi Graham sorry to bother you but I have a question. I have a SD 1 Vitesse engine running in my p6 . With the su hif6 carbs. I think I have the bac needles in it. What would you recommend for this engine. Thank you very much for your experience and great videos . Kind regards Marc.
Thanks for the video, that is a big old chunk of driveability the su carbs have over the 4 barrel "as tested" 200 and a bit horsepower would of been a good street engine hp not so long ago.
"as tested" the jetting in the 4 barrel might of left a very small amount of power low down in the rev range on the table, but it really woulnt of been much
I've got a series 2 1960 swb Land rover That I fitted a 3.5 think it was range rover/ defender spec engine on carbs I changed to SU from Stromberg's It went ok but I blew it up Now I'm going 3.9 injection engine I'm fitting inlet and carbs off my 3.5 I've bought from RPI a fast road cam BP270 I wash thinking torque Max But they Said for my mostly road use Fast road be fine Su are on standard needles They will need changing Last engine think was about 135 3.9 fast cam on su carbs What power do you think it will make And any suggestions please Cam's not fitted yet
You mean a Piper cam ( Pipercross make air filters) how well it works will depend on which can you choose, whatever cam you pick though you have to bear in mind the P5 auto gearbox wont take kindly to anything other than a very mild cam. This test seems to bear out what most say, the 4 barrel will loose low end power, and im my experience anything other than a very very mild cam will also loose you low down torque. So with that in mind i would probably stick to a standard or 3.9 discovery cam
@PenguinMotors thank you for your reply (love watching all your videos). I don't want a big increase in power so when I get round to checking the push rods and shim buckets I will take your advice. The car has good and even compression but sounds a bit tappety.
300 bhp is a fairly big ask from a Rover V8, in 3.5 form that is a full race engine. Make the engine bigger it becomes easier, although still not a walk in the park, bigger capacity increases torque a lot, but it cuts down the engines ability to rev, so you end up with torque monsters but still no real power
@@PenguinMotors I've built a few road going 4.6 engines, i.e. they still need to idle well and pull from low RPM, the last one I built (running a re-calibrated 500 carb) pushed out 315 BHP.
your not wrong they are the same CV (constant velocity) design as bikes, only differnce is bikes use a lightweight slide and diagrpagm and Su uses a heavy piston, and a stromberg carb is somewhere inbetween
Another great video Graham, I really enjoy these and appreciate the effort you go to to show the typical mod’s people do with the real world outcomes.
Great video again, its a good job the heads are a little restrictive with the cast crank and rods, I bet they make a loud bang when they let go.
Elderbrock make a great carb. But those old SU's still get the job done on some engines. Fascinating comparison on a good spec V8
i think the dyno curves are more a reflection of the intake manifolds (runner length) than the carburetor type.
of course, they are related as the carbs are specific to the manifolds.
Although, as an experiment, the SUs could be adapted to the Edelbrock manifold.
The Edelbrock manifold exhibits the typical short runner dyno curve.
I agree that the SU set up is better for heavy car, automatic transmission use.
In a light-weight car (Morgan for example), the 4-barrel type manifold would be better.
Thanks for these videos. I'm seeing very different use cases here for manual and automatic cars. With my auto i hardly ever use more than 3,500rpm and it's clearly spent much over 4,000rpm. I can imagine as standard, the manual is a little bit dull (it's basically a diesel!) and a cam and 4 barrel if nothing else will make it more fun to rev out. But it's clear as most P6s are autos, people need to stop and think because it's easy to make the car worse for general driving with conventional tuning. I'm seeing the 3.9/4.0 as a sweet spot for a build. I'd like to go for a hotwire setup on 4 hole injectors, because I really like the drivability of EFi and I know how to program the 14CUX.
I think 3.9/4.0 is a good choice, I recently dyno’d one, it was tired and literally had bugger all oil pressure but still churned out more power than most 3.5 along with tons more torque
Excellent video!
I wonder what these ran on in the original Buick cars? 2 barrel?
two barrel, ive actually got an origonal Buick manifold which i have just redrilled to take a 38 dgas weber
Yes.I have a Rochester 2GC on a Buick intake on my TR8
An interesting video, however a better comparison is to switch out the carbs using the same inlet manifolds.
That would be interesting but it’s something few people would be able to do, I like to test things that are commonly done
thankyou
Hi Graham sorry to bother you but I have a question. I have a SD 1 Vitesse engine running in my p6 . With the su hif6 carbs. I think I have the bac needles in it. What would you recommend for this engine. Thank you very much for your experience and great videos . Kind regards Marc.
comparing BAF i used and BAC, BAF is quite a bit richer in the midrange and at lower rpm but leaner at the top end
Thanks for the video, that is a big old chunk of driveability the su carbs have over the 4 barrel "as tested" 200 and a bit horsepower would of been a good street engine hp not so long ago.
"as tested" the jetting in the 4 barrel might of left a very small amount of power low down in the rev range on the table, but it really woulnt of been much
Cheers
I've got a series 2 1960 swb Land rover
That I fitted a 3.5 think it was range rover/ defender spec engine on carbs I changed to SU from Stromberg's
It went ok but I blew it up
Now I'm going 3.9 injection engine
I'm fitting inlet and carbs off my 3.5
I've bought from RPI a fast road cam BP270
I wash thinking torque Max
But they Said for my mostly road use
Fast road be fine
Su are on standard needles
They will need changing
Last engine think was about 135
3.9 fast cam on su carbs
What power do you think it will make
And any suggestions please
Cam's not fitted yet
3.9 with a mild cam and su’s you should see something like 170/180bhp and 240lbft
What do you think of the Pipercross cam in a P5B (with the Edelbrock)?
You mean a Piper cam ( Pipercross make air filters) how well it works will depend on which can you choose, whatever cam you pick though you have to bear in mind the P5 auto gearbox wont take kindly to anything other than a very mild cam. This test seems to bear out what most say, the 4 barrel will loose low end power, and im my experience anything other than a very very mild cam will also loose you low down torque. So with that in mind i would probably stick to a standard or 3.9 discovery cam
@PenguinMotors thank you for your reply (love watching all your videos).
I don't want a big increase in power so when I get round to checking the push rods and shim buckets I will take your advice.
The car has good and even compression but sounds a bit tappety.
if it is tappety the cam, followers and rockers will all be worn out
so, is 300+ hp hard to do on these engines ?. would be fun to put in a boat because of the weight. but need a bit more hp
300 bhp is a fairly big ask from a Rover V8, in 3.5 form that is a full race engine. Make the engine bigger it becomes easier, although still not a walk in the park, bigger capacity increases torque a lot, but it cuts down the engines ability to rev, so you end up with torque monsters but still no real power
The thing to remember is a 3.5 is only about 210 cubic inch.
@@PenguinMotors I've built a few road going 4.6 engines, i.e. they still need to idle well and pull from low RPM, the last one I built (running a re-calibrated 500 carb) pushed out 315 BHP.
Su carbs aint so bad. Like a motorcycle carb as i see it. maybe i am wrong
your not wrong they are the same CV (constant velocity) design as bikes, only differnce is bikes use a lightweight slide and diagrpagm and Su uses a heavy piston, and a stromberg carb is somewhere inbetween