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Federal 45 DHLA cars on restrictor plates?


f1karting

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OK heres one.. I am in process of rebuilding the 45 DHLA on my 'new' 85 TE and notice the OE carb spacers are 40mm ID and include an anti reversion ring machined into the downstream face. :D

I decide to order the proper ones for the 45 and guess what.. the same dammed parts appear in the post. :D

It turns out that those are the OE fitment on US fed cars.. at least they are the PN shown in the book. I dont buy into that being the best setup for performance, as the spacer ID and ring protrude into the intake stream like a 40mm restricter plate. :lol:

Because Lotus apparently dont make a 45mm spacer for the 45, I am now forced to adapt the cosworth style molded o-ring setup to improve the gas flow thru the section. I will need to make a spacer block to sandwich between 2 of the orings on each barrel to get the offset to match OE so the turbo plumbing aligns with the compressor outlet. :lol:

Whats with that?? Has anyone ran into this before? And if it is OE why?

Confused (again) Jan

Edited by f1karting

If you set no goals you shall surely reach them..

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Jan,

I really want to know if the same 'plates' are on my car! :unsure: My curiosity is peaked!

Thanks for the tip!

Cheers, Lee

PS. I don't think there is any hydrogen peroxide in the D-Rust-It, rust remover. It doesn't fizz on your fingers when you stick them in it :( . I looked on their website and didn't see anything that would indicate it's presence either. I did note, however, that they have a toll free number now. Maybe you should give them a call.

Edited by Esprit Aviation
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OK heres one.. I am in process of rebuilding the 45 DHLA on my 'new' 85 TE and notice the OE carb spacers are 40mm ID and include an anti reversion ring machined into the downstream face. :(

I decide to order the proper ones for the 45 and guess what.. the same dammed parts appear in the post. :)

It turns out that those are the OE fitment on US fed cars.. at least they are the PN shown in the book. I dont buy into that being the best setup for performance, as the spacer ID and ring protrude into the intake stream like a 40mm restricter plate. :unsure:

Because Lotus apparently dont make a 45mm spacer for the 45, I am now forced to adapt the cosworth style molded o-ring setup to improve the gas flow thru the section. I will need to make a spacer block to sandwich between 2 of the orings on each barrel to get the offset to match OE so the turbo plumbing aligns with the compressor outlet. :(

Whats with that?? Has anyone ran into this before? And if it is OE why?

Confused (again) Jan

They are there to speed up low rpm inlet gas flow to increase torque and drivability (throttle response).

I have also seen similar types of plate on other carburetted performance street cars, with high lift cams and big carburettors.

The engine would ultimately develop more top end power without them, but I think it will be lousy to drive around town (below 2000 rpm)

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Wayne,

That certainly makes sense. I've never had the carbs off in all the time I've owned my Esprit, so I would have never seen them. First time for everything!

Do you know if by chance these types of plates would be similar to the ones sold to owners of normally aspirated Esprits for anti-reversion purposes? They are supposed to cut down on the 'knocking sound' back up the intake tracts, due to the supersonic wave created as the intake valves close.

I may be way off technically on that, but it is merely what I have heard.

Thanks for the input!

Lee

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They are there to speed up low rpm inlet gas flow to increase torque and drivability (throttle response).

I have also seen similar types of plate on other carburetted performance street cars, with high lift cams and big carburettors.

The engine would ultimately develop more top end power without them, but I think it will be lousy to drive around town (below 2000 rpm)

Wayne.. I cant subscribe to that idea for some reason. It just doesnt make sense from a gas flow POV.. the 40mm diameter section length is only about 10mm; so small in comparison to the overall tract length, that the flow velocity increase profile would be too short to be much use in increasing overall tract gas flow velocity, IMO.

With the insight of your observations, I could rationalize their benefit in adding turbulance to the gas stream and perhaps improved atomization at low velocities. Maybe the goal was to be able to run a leaner jet for improved low speed emissions/ economy, yet maintain driveability by improving gas mixing at low speed?

What I have used on other tuned engines, were anti reversion intake valves.. those worked very well in impeding reverse flow effects from cams with larger overlap... but to add AR into the intake manifold.. I dont know.. the esprit cams are hardly 'performance' profiles.

I am surprised that if low speed performance was an issue with the 45 carb then why did Lotus use them vs the 40s as used in DOM/ ROW engines? The 45 choke sizes are realistically sized for the application according to sources Ive read.

I see the restriction as an added loss that the turbo has to overcome at peak boost, hence more charge temp for a given output... I guess it all had to be weighed out in the original technical design of the car.

I guess Ill find out once I try the car without the OE spacers.

Any Nascar engine tuners out there that can shed some light on restrictor tuning?

J

Edited by f1karting

If you set no goals you shall surely reach them..

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Wayne.. I cant subscribe to that idea for some reason. It just doesnt make sense from a gas flow POV.. the 40mm diameter section length is only about 10mm; so small in comparison to the overall tract length, that the flow velocity increase profile would be too short to be much use in increasing overall tract gas flow velocity, IMO.

With the insight of your observations, I could rationalize their benefit in adding turbulance to the gas stream and perhaps improved atomization at low velocities. Maybe the goal was to be able to run a leaner jet for improved low speed emissions/ economy, yet maintain driveability by improving gas mixing at low speed?

What I have used on other tuned engines, were anti reversion intake valves.. those worked very well in impeding reverse flow effects from cams with larger overlap... but to add AR into the intake manifold.. I dont know.. the esprit cams are hardly 'performance' profiles.

I am surprised that if low speed performance was an issue with the 45 carb then why did Lotus use them vs the 40s as used in DOM/ ROW engines? The 45 choke sizes are realistically sized for the application according to sources Ive read.

I see the restriction as an added loss that the turbo has to overcome at peak boost, hence more charge temp for a given output... I guess it all had to be weighed out in the original technical design of the car.

I guess Ill find out once I try the car without the OE spacers.

Any Nascar engine tuners out there that can shed some light on restrictor tuning?

J

Well Jan, I guess I fell into your trap of answering your retorical question! :huh:

Nobody else was answering so I thought I would give it a go :o

I was going to add I thought they might be to restrict the hot exhaust gasses from traveling back all the way to the carbs, as I read somewhere (In one of Tony Rudds Technical papers )that the 907 series Lotuses camshaft timing had an amount of EGR built in to it(negating the need for the engine to have a separate EGR valve mounted to it), but I might also be wrong about that.

Similar principle to This?

Edited by WayneB
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I have no idea what they are for but Wayne's suggestion that they are there because of the internal EGR effects they would give sounds most likely.

S4 Elan, Elan +2S, Federal-spec, World Championship Edition S2 Esprit #42, S1 Elise, Excel SE

 

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JAE sells something similar for the normally apirated Esprits. A friend in Canada put them on his S2 to quiet a loud rapping noise, that JAE thought was a shock wave travelling back up the intake runners when the intake valve slams shut. Unfortunately, it didn't change the noise or performance. He has since torn the engine down and never found the source of the mysterious noise!

Anyway, has anyone heard of an application such as this?

The search for the truth continues! Carry on!

Lee

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What I have used on other tuned engines, were anti reversion intake valves.. those worked very well in impeding reverse flow effects from cams with larger overlap... but to add AR into the intake manifold.. I dont know.. the esprit cams are hardly 'performance' profiles.

Tell us some more about these "anti-reversion" intake valves (who makes them for instance)

Heres a little article on anti reversion cones in the inlet manifold

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Tell us some more about these "anti-reversion" intake valves (who makes them for instance)

Heres a little article on anti reversion cones in the inlet manifold

Thanks for your input Wayne.. didnt mean to give you a hard time back there.. B)

The AR valves I used were on a Cooper S I built back in the late 80s. The valves were made by APT (David Vizard, Dave Anton) in Riverside, CA. They were basically a custom SS valve that had a machined 'trough' for lack of a better word, on the perimeter face of the valve, creating a poorly flowing valve in backflow conditions.. similarly for the exhaust valve, the face edge had a nice generous radius to facilitate flow out of the chamber into the port. They worked well.

The headers had the 'cones' on them which flowed well in the correct direction but lousy in backflow. As it turns out, the sharp edge 'break away' on such devices, actually loose very little energy as flows exit them, but create huge losses in reverse.

The Cooper S I had was a seriously tuned road car that had a special steel billet cam made by crane, designed by APT, it had a huge base circle with very rapid ramp rates, high lift and duration, and the engine would pull clean from 2300 foot flat, and pull hard to 8000 without complaining. I was impressed to say the least.

I have actually taken stock valves and machined in the AR with reasonable success. I dont think the Turbo Esprit would benefit from the intake AR, but could from the exhaust flow improvement of a radiused face. A tuned NA 907 with hot cams may be worth a try.

J

Edited by f1karting

If you set no goals you shall surely reach them..

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I was going to add I thought they might be to restrict the hot exhaust gasses from traveling back all the way to the carbs, as I read somewhere (In one of Tony Rudds Technical papers )that the 907 series Lotuses camshaft timing had an amount of EGR built in to it(negating the need for the engine to have a separate EGR valve mounted to it), but I might also be wrong about that.

Similar principle to This?

I guess it all helps keep things moving in the direction its suppose to.. I would be curious to know if and how it effects the wave dynamics in the ports and manifold.

I think TR comments have to do with the fact that the cam timing being retarded to 110 vs 104. [which I understand serves the purpose (to some degree) of 'EGR'].

Edited by f1karting

If you set no goals you shall surely reach them..

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JAE sells something similar for the normally apirated Esprits. A friend in Canada put them on his S2 to quiet a loud rapping noise, that JAE thought was a shock wave travelling back up the intake runners when the intake valve slams shut. Unfortunately, it didn't change the noise or performance. He has since torn the engine down and never found the source of the mysterious noise!

Anyway, has anyone heard of an application such as this?

I could see that to some very small degree.. however, the noise is mostly from pressure pulses in the intake system, not so much the valve shutting.. Webers are notorious for enhancing that noise. (which I do like BTW) Not much you can do except muffle it.. like Lotus did on the MK2 lotus cortina.. added a honkin big muffler on the intake system to quiet the intake noise from the webers on the twin cam.

Edited by f1karting

If you set no goals you shall surely reach them..

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  • 8 months later...
OK heres one.. I am in process of rebuilding the 45 DHLA on my 'new' 85 TE and notice the OE carb spacers are 40mm ID and include an anti reversion ring machined into the downstream face.

I decide to order the proper ones for the 45 and guess what.. the same dammed parts appear in the post.

It turns out that those are the OE fitment on US fed cars.. at least they are the PN shown in the book. I dont buy into that being the best setup for performance, as the spacer ID and ring protrude into the intake stream like a 40mm restricter plate.

Because Lotus apparently dont make a 45mm spacer for the 45, I am now forced to adapt the cosworth style molded o-ring setup to improve the gas flow thru the section. I will need to make a spacer block to sandwich between 2 of the orings on each barrel to get the offset to match OE so the turbo plumbing aligns with the compressor outlet.

Whats with that?? Has anyone ran into this before? And if it is OE why?

Confused (again) Jan

An update from a previous discussion...

I replaced these as well with normal 45mm diameter cosworth isolators.. no dyno comparison tho... the cosworth ones need to be quite snug and do seep a little fuel on boost. Better solution may be to machine the original 'restrictor' out or make new spacers and use the nice fat o-rings lotus have.

Sandwich plate not required BTW

Edited by f1karting

If you set no goals you shall surely reach them..

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Jan,

Was this mod done before or after your dyno runs in the post discussing fitment of short trumpets?

Could you include some pics of this process?

Before unfortunately.. so no back to back testing.. I am not sure what process you would like pix of??

If you dont have to kill me if you tell me.. how did you get over 400 lbs out of you car?

Go lite or go home, I say! ... CABC would love us.

If you set no goals you shall surely reach them..

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I wondered if you had pics of the restrictor plates for those of us who have not had their carbs off. Will you do a dyno run w/ the restrictors in place along w/ the 16mm trumpets to isolate the specific gains from each mod?

In re: to the weight loss, sometimes it is hard to remember, as it took a period of about ten years! I have gone soooo extreme w/ taking weight out, that the interior looks like a car that is only meant for the track. Much of the weight removal descriptions are in my garage, but I've done quite a bit of small stuff lately that seems to add up. I'll try to compile a list when time permits. I do believe that despite the extreme I have taken it to, that Colin would approve. I will be installing some sort of a lightweight interior asap, and will continue to design a light window regulator for the pass side and things like that. I'm pretty much starting w/ a clean slate, and would like to add amenities where feasible.

The best thing about lightness is that it obviates the need to overstress the engine/trans, brakes, suspension... literally every component, to achieve the same performance, plus it usually saves many$$$!

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I wondered if you had pics of the restrictor plates for those of us who have not had their carbs off. NO I DONT BUT I COULD TAKE SOME. Will you do a dyno run w/ the restrictors in place along w/ the 16mm trumpets to isolate the specific gains from each mod? I WASNT PLANNING TO BOTHER TESTING WITH THE PLATES IN.. TOO MUCH HASSLE AT THIS POINT AND I DONT GET A SENSE THAT THEY ARE ANY GOOD FOR POWER.. PERHAPS BETTER ECONOMY AND EMISSIONS (WHICH WE CANT REALLY TEST). I CAN TELL YOU THE PLATES ARE 40mm ID AND PROTRUDE INTO THE AIRSTREAM MORE THAN WHAT LOOKS ACCEPTABLE. I BELIEVE THE PLATES WERE DESIGNED FOR THE DOM/ROW 40DHLA AND SIMPLY USED ON THE 45DHLA FED CARS BECAUSE THEY COULDNT BE BOTHERED TO MAKE SPECIAL ONES FOR THE 45. (ALTHOUGH I COULD BE WRONG)

IN CASE YOU WERE WONDERING, THE TESTING ON THE LONG VS SHORT STACKS WAS DONE WITHOUT THE RESTRICTOR PLATES. I DONT THINK THAT THE OE SETUP IE: LONG STACKS WITH THE PLATES WOULD HAVE BEEN BETTER THAN THE TEST WE DID WITH LONG STACKS ALONE.

In re: to the weight loss, sometimes it is hard to remember, as it took a period of about ten years! I have gone soooo extreme w/ taking weight out, that the interior looks like a car that is only meant for the track. Much of the weight removal descriptions are in my garage, but I've done quite a bit of small stuff lately that seems to add up. I'll try to compile a list when time permits. I do believe that despite the extreme I have taken it to, that Colin would approve. I will be installing some sort of a lightweight interior asap, and will continue to design a light window regulator for the pass side and things like that. I'm pretty much starting w/ a clean slate, and would like to add amenities where feasible.

The best thing about lightness is that it obviates the need to overstress the engine/trans, brakes, suspension... literally every component, to achieve the same performance, plus it usually saves many$$$ I LIVE THAT PHILOSOPHY !

..IT IS AMAZING HOW MUCH WEIGHT CAN BE ACTUALLY BE TRIMMED OFF.. THE HOOD AND BONNET COVERS ALONE ARE INSANELY HEAVY.. MY NEW CF VERSIONS WILL BE WORTH THE EFFORT.

Edited by f1karting

If you set no goals you shall surely reach them..

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Jan,

First of all thanks for answers to all the questions! Only a couple more!

Don't worry about pics if you don't already have them, no sense in taking it apart. I think I will lose my restrictors and go w/ the short trumpets. Have you noticed any difference in normal around town driving, either good or bad?

So your dyno graphs/gains are strictly due to the fitment of the short trumpets? Did you get any real world, seat-of-the-pants feeling from removal of the restrictors alone, before the short trumpets were installed?

I would love to get my hands on @ least a back hatch complete w/ louvers in CF!

Edited by Esprit Aviation
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Jan,

I just updated my garage area w/ all the mods I can think of so you can get some idea as to where all the weight went.

Just remember it is a fairly raw, but quite drivable car @ this point. It is also fast enough to make me wonder if I should take it any further. I'm sure there are many drivers out there that would be very comfortable @ this level, but my perception is that the acceleration is becoming disconcerting, @ least for street purposes. I will, more than likely, install a full cage asap. I'm just not sure where to begin w/one.

Lee

Edited by Esprit Aviation
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Jan,

First of all thanks for answers to all the questions! Only a couple more! ITS ALL GOOD!

Don't worry about pics if you don't already have them, no sense in taking it apart. I think I will lose my restrictors and go w/ the short trumpets. Have you noticed any difference in normal around town driving, either good or bad? VERY GOOD EXCEPT FOR THE SMALL PROGRESSION HESITATION I AM WORKING OUT..

So your dyno graphs/gains are strictly due to the fitment of the short trumpets? YES Did you get any real world, seat-of-the-pants feeling from removal of the restrictors alone, before the short trumpets were installed? NO. I REMOVED THE RESTRICTORS AS PART OF THE CARS RESTORATION PROGRAM.. CAR WAS NOT DRIVABLE WHEN I GOT IT.. SO NO 'BEFORE' TESTING..

ONCE I GOT HER ROADWORTHY, I DID DRIVE IT INITIALLY WITH FACTORY JETTING, WITHOUT THE RESTRICTORS, AND IT WAS ONLY DRIVABLE ON LIGHT THROTTLE AND WOULD NOT TAKE WOT AT ALL.. INITIALLY (SEAT OF PANTS TUNING) I WENT TO 58-IDLES AND 175-MAIN JETS TO MAKE IT DRIVABLE.. I AM NOW AT 42-PUMP, 55-IDLE, 185-MAIN AND WILL LIKELY NEED 250-AIRS TO LEAN OUT THE TOP END.

I DRIVE THE CAR PRETTY HARD MOST OF THE TIME SO IT DOES USE FUEL LIKE A V8.. BUT IT DOES PULL LIKE ONE TOO.

I would love to get my hands on @ least a back hatch complete w/ louvers in CF! I AM IN PROCESS OF MAKING SOME MOLDS.. I HAVE A LOUVER MOLD 95% COMPLETE AND AM DOING THE FINAL BODYWORK ON THE FRONT AND REAR TAILGATES AT THE MOMENT TO USE THEM AS MASTERS. NEXT YEAR I HOPE TO HAVE SOME INITIAL PARTS PULLED. RIGHT NOW I HAVE THE RAD SHROUD AND UNDERTRAY MOLD READY AND HAVE BUILT A CF/KEVLAR RAD SHROUD..SEE GARAGE AREA.

If you set no goals you shall surely reach them..

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Jan,

How much did the 16mm stacks cost from DB? If you had to venture a guess, what would the result be of fitting 25mm stacks? It seems as if it would be enough to allow free flow to the throats.

Edited by Esprit Aviation
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Jan,

How much did the 16mm stacks cost from DB? If you had to venture a guess, what would the result be of fitting 25mm stacks? It seems as if it would be enough to allow free flow to the throats.

I have contacted DBE and they say they have more stacks coming.. didnt ask the price.. I think at the time they were about $20 each... Ken Grey is my contact at DBE.

I think the 25mm will give similar results.. If I can get some Ill test them.

Edited by f1karting

If you set no goals you shall surely reach them..

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  • 2 weeks later...
Hi F1Karting

I was reading your threads about your tuned cooper engine. I done much the same with oversize valves high lift cam etc. In Uk those one way valves are called rimflo valves. Those mods with my straight though pipe used to really bark as soon as you hit 3000 rpm

yup..rimflo was it.

If you set no goals you shall surely reach them..

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