Old Janspeed set up

bula · Post by **bula** » Tue Sep 04, 2012 3:38 pm

wow now thats opened a can of worms! General feeling is I cant use a redtop now proof I can

Trial and error now I suppose. Being that this is an old setup the only way I think of controlling the boost is this outlet on the top of the plenum exiting on the right has a plate bolted with a spring I assume will bleed off excess pressure, more as its tightened up less as its loosened off. Assuming the carb is setup as a blow through, answers have come to suggest the inlet pressure is to great for the pressure of the petrol to enter the system, this would definately cause the drivability issues im experiencing cruising about, hardly any throttle, behaves sociably put your foot down and it dies. Many thanks for the replies people, think Im going to go minimum boost and give it a go, just so as I can use it while I save some pennies for a swirlpot and 3bar injection pump. So fingers crossed!

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chodjinn · Post by **chodjinn** » Tue Sep 04, 2012 3:55 pm

Definitely sounds as though your carb is not set for +ve pressure.

That thing on the side of the plenum looks to be a crude blow-off or dump valve. You would be much better suited getting rid of it and fitting an off-the-shelf dump valve with a spring set to the desired psi. You coulf fit it between the turbo and plenum, then block off the existing part on the right.

Yours is a blow through set up, so either the carb needs setting for forced induction (sounds like it's not) and get a high pressure pump. I bought a Bosch motorsport fuel pump (serial number ended with "910") from ebay brand new for £50, that will more than do you.

Bear in mind you'll need a return line to bleed off the excess fuel (does the Malpassi rising rate regulator already have one?).

Fitting a holley carb will also require a new inlet manifold - expect £500+ second hand, double that new.

Keep it simple, moving to EFi is a big big changes and takes longer and much more money than you think - trust me, if I'd have stuck with carbs I'd still have a twin turbo V8 in my MGB rather than an empty engine bay

Darkspeed · Post by **Darkspeed** » Tue Sep 04, 2012 5:56 pm

I think you will find that the thing on the side is a fuel pressure regulator - It looks like a fixed regulator which is not suitable at all if it is.

For that set up you need a fuel pressure regulator with pressure feedback from the manifold so that it delivers fuel at a fixed pressure (2-3psi) above the manifold pressure, and therefore the float bowl pressure, at all times. If the fuel pressure is fixed at say 13PSI when the manifold pressure is at 3psi you are putting 10PSI at the needle valve which may overfill the float bowls.

Likewise there should also be manifold pressure to the Vacuum on the dizzy to retard the ignition when under boost.

Had a TT blow through with a DCNF type on a Pinto. the float bowl is usually sealed with pressure balance taps epoxied in and taken up into the plenum cap. Malpasi pressure tap regulator - think I still have it if you want a picture - ran a Bosch high pressure pump

EDIT - If I can find the pump filter and regulator - want to swap for the Facet?

Andrew

bula · Post by **bula** » Tue Sep 04, 2012 10:10 pm

Sorry for any confusion you lot but I took that pic when swapping over the normal sytech regulator and the malpassi rising rate one that's the one far right of engine bay. Have run a return line back from this to the filler neck of my tank, it has a vented cap also so no vacuum will be created as the fuel drains. A pic of the +ve pressure carb would be great if you had one as there doesn't seen to be as much love shown toward the DCNF as the Holley lol

chodjinn · Post by **chodjinn** » Wed Sep 05, 2012 8:34 am

Darkspeed wrote:I think you will find that the thing on the side is a fuel pressure regulator - It looks like a fixed regulator which is not suitable at all if it is.

No, we were talking about the part at the direct right of the plenum in the photo - the bit of blue silicon hose and pipe.

I know what a fuel pressure regulator is and I wasn't talkinG about that!

Darkspeed · Post by **Darkspeed** » Wed Sep 05, 2012 9:01 am

Winds neck in and leaves - "clunk"

chodjinn · Post by **chodjinn** » Wed Sep 05, 2012 9:07 am

Darkspeed wrote:Winds neck in and leaves - "clunk"

ha sorry didn't mean my reply to come across like that mate! Busy morning and trying to avoid work ... hehe!

Darkspeed · Post by **Darkspeed** » Wed Sep 05, 2012 12:23 pm

No worries - I should not post when I only have the time to skim read and not the time to read through. If I had taken the time I would have spotted the second reg and noted that it was not a twin turbo set up with only one half installed

and that was as you say a crude PRV

A quick final note -may has also been covered as I am posting in a hurry again - No intercooler may lead to fuel boiling.

chodjinn wrote:
Darkspeed wrote:Winds neck in and leaves - "clunk"
ha sorry didn't mean my reply to come across like that mate! Busy morning and trying to avoid work ... hehe!

chodjinn · Post by **chodjinn** » Wed Sep 05, 2012 1:30 pm

On a draw-thru / suck-thru system you can't fit an intercooler as there is a risk that the fuel would drop out of suspension and potentially cause an explosive hazard! Drawing the fuel into the turbo(s) actually helps cool them down.

On a blow-thru set up, you can fit an intercooler, so Bula can fit one if he so wishes. You can run turbo set ups without intercoolers, as long as you don't go crazy with boost etc.

Darkspeed · Post by **Darkspeed** » Wed Sep 05, 2012 5:53 pm

chodjinn wrote:
On a blow-thru set up, you can fit an intercooler, so Bula can fit one if he so wishes. You can run turbo set ups without intercoolers, as long as you don't go crazy with boost etc.

Unfortunately with the blow through set up on that car the float bowl is attached directly to the carb and will get hot very quickly - My Pinto ran a huge intercooler with fresh air feed - The carb was away from the engine not sitting in a Vee and the manifold heating was blanked off in order to keep it all as cool as possible.

What can happen is that the fuel can get heated quickly when under boost but being under pressure stops it vapourising however when the boost is dropped the fuel can flash to vapour.

As you say suck through has its own issues - but a blow through configuration like this without an intercooler is not a great idea and I would guess that with the additional pumping losses that this system would not produce much in the way of extra power over N/A

bula · Post by **bula** » Thu Sep 06, 2012 7:02 am

Trial fit, not its final resting place as too low but should cool enough. Have experienced the fuel boil phenomenon! A bit unsettling to be honest lol thought it was an airlock in the rad pipes to start with could hear this bubbling noise but wasnt clear where it was coming from untill I thought I'll just take the plenum off??? Quick mumble to the other half, Is that fire extinguisher still in the cupboard under the stairs? Would you mind getting it for me as F#?N QUICK AS YOU CAN...... please!!!!!!

Will bang it on youtube if anyone wants a laugh "TR7V8 petrol boil"

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Darkspeed · Post by **Darkspeed** » Thu Sep 06, 2012 12:36 pm

Looks like you have most of the pitfalls that I am aware of with this type of installation well covered and cannot fault the cold air feed to the intercooler

Great description by the way

How is the ignition timing control taken care of?

Edit - Looking at it that Intercooler looks very much like the Cossy type that was fitted to my set-up.

bula · Post by **bula** » Fri Sep 07, 2012 7:54 pm

That, believe me is more by luck than judgement

Have just got a new dizzy from powerspark as with everything else thats happened over the last few weeks now it decides not to start! The original dizzy is a 35 DM the one with a constant energy unit that sits under the coil but the other day was trying to set the timing with a strobe and not getting anything

checked all connections etc still nothing and as I'd not changed anything on the ignition side figured it had seen better days. That would'nt have helped the rough running ha ha. Signs of corrosion inside the plastic cap also. Have now got the newer type 35 DLM with amplifier on the side of the dizzy body for a reasonable price off ebay so will get around to fitting that over the weekend hopefully. Incidentally the intercooler and pipework were off there too, 120 notes for core, mandrel bent alloy pipe work, silicon joiners and clamps, bargain! Well as long as it works

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Darkspeed · Post by **Darkspeed** » Sat Sep 08, 2012 4:55 am

My set-up ran a "vacuum" connection from the manifold plenum to the dizzy using an air line pressure connection one of those small bore push fit type connections like on disposable mig gas bottles. This went to the vacuum port on the dizzy and the vacuum advance was modified/set so that it retarded under boost as well as advancing under vacuum.

I never checked the amount of mechanical advance it had or the max and min advance retard degrees but it was modified from standard as the bob weights were welded and hand filed as was the A/R slot in the dizzy baseplate

Looks like there are plenty of other boost retarder systems available such as the NOS guys on here use

ETA

Just thinking about the air pressure connection - makes sense - if the hose blows off from that manifold plenum connection its fuel air mix under pressure coming out - would be like a mini gas torch if it lit under boost

Which also drew me back to your picture - is your brake servo connected to the manifold plenum? Mine had the servo removed and converted to a non vac bias set-up.
My be worth thinking about a diesel motor alternator - which I always fancied trying out for a sort of PCV application as its engine speed dependent but unlikely to have sufficient capacity.

Andrew

bula · Post by **bula** » Sun Sep 16, 2012 1:35 pm

Alternator was upgraded from the Triumph one to a RR pattern, think it was around 85A but theres not much drawing on it apart from ignition, no stereo, no leccy windows, aircon etc so should be plenty. Servo and master cyllinder are upgraded too from a Sherpa twin wheel bus too allow for the extra fluid/pressure needed for the Vitesse 4 pot calipers. The vac connection is tapped into the inlet manifold with the other one, originally for difflock on the RR, blocked off.

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