Engine and Transmission Tech

Thought I'd share a picture of cleaning up some Rover/Buick intakes in preparation for some dyno testing.

From another angle:

Good thing we aren't in the same city Dan, could be dangerous.

Jim

What is that LARGE port manifold, top right, pic #1 ? We appreciate your efforts.
Art.

> Good thing we aren't in the same city Dan, could be dangerous.

Dangerous but in a good way (but not for the neighbors).

> What is that LARGE port manifold, top right, pic #1 ?

That's a 1971 Ford Boss 351C aluminum dual plane intake. It was also fitted to the 1972 HO 351C. An iron version was fitted to standard 351C-4V engines. I had it sitting next to a Rover intake to illustrate the port size differences. The 351C-4V has 2.19"/1.71" diameter valves and ports bigger than many big blocks but the heads were used on engines down to 302 cubic inches (Boss 302). With about $150 labor in short side radius work, factory 351C-4V heads will flow over 320 CFM compared to a Rover at maybe 125 CFM. The ports are really too large for most applications and Ford's racing derivatives got progressively smaller port sizing. That said, through a stroker crank at them for 400+ cubic inches and they really come alive.

> We appreciate your efforts.

I still need to come up with a source for larger diameter trumpets for the Rover EFI intake before I can start testing. Not pictured above is an Edelbrock Performer Rover dual plane but I've got a stock one and one that has been extrude honed to test.

Dan

Sometimes a muffler shop can bell out tubing into an acceptable shape.

Jim

Did I mention I have a Hilborn Inj. for 215+. It has 1.8" butterflies. No trumpets.
Art.

I’ve also been struggling to locate some inlet trumpets that appear to be value for money and begrudge spending that much from the UK.
I don’t believe they need to be significantly larger than they are; The twin throttle plenum system homolated for the last of the ‘85 & ‘86 SD1 vitesses for touring car duty, had 41mm vs 38mm trumpets - but also use a wider plenum base (and a twin intake plenum) to increase volume and area around the (larger) trumpets.


Personally, I am going to try this in the near future as I have a lathe and feel like this would be easy.
[youtu.be]

Don’t forget about modifying the dogleg on the lower EFI manifold (if chasing high flow)

This is a pic of the twin plenum (or more correctly termed the twin throttle plenum) trumpet / base.

These use the standard lower inlet manifold but the plenum base is 20mm wider...
The trumpets are also 3/4” shorter than the standard plenum.





I'm sure youve come across this site - he seems to update it as new stuff appears.
[www.mez.co.uk]



Edited 2 time(s). Last edit at 07/11/2021 11:59AM by turbodave.

Dave, I did a set of trumpets years ago. Instead of annealing I simply used a hydraulic press and pressed the top of trumpet with a similar conical arbor as in the video. I have absolutely no idea what series aluminum I had but definitely weldable.

Again, no idea about the performance gains over srd setup but on psychological scale they must be huge. That 4.6 engine with Merlin heads put out 314 hp at flywheel on rolling road. I'll upload a photo soon.

Was the 314hp you mention on the standard trumpets? I thought the Merlin head didn't use the standard inlet manifold - or am i getting mixed up?

Nope, with larger/shorter trumpets, ported intake and 75 mm front mounted throttle body. Merlins accept normal Rover intakes. Wildcats and TA heads are another story.

AIR., my McKenzie ported Merlin Int. flowed 220+/- cfm @ 28", .600 lift ? Art.

What kind of HP figures have you got with them, Art ?



Edited 1 time(s). Last edit at 07/14/2021 01:30PM by minorv8.

Zero. Working on 4340 forged crank and a built, 6V71 supercharger, with the Merlins, ( they are pretty thick). Likely my first motor
for 51' Buick Special, lead sled without lead. Buick with Buick = nice ring to it. Art.