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f1karting

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Posts posted by f1karting

  1. I would say that the distance is sufficient too, but what is not so good is the airflow path into the trumpets because of their relatively sharp edges causing turbulence as I tried to explain badly in my last post - here is a marked up photo of what I meant, I believe this would give similar results - done on all 4 trumpets of course!

    Phil

    98GT3

    This is what Richard Jenvey at Jenvey Dynamics writes:

    "The air horn serves three main purposes; 1) To convert the pressure difference between bore and entrance into air velocity with the minimum of energy loss. 2) To act as the interface between the induction system and the atmosphere, i.e. the point at which pressure waves change sign and direction. 3) To complete the system to the required overall length.

    For ease of description the air horn may be considered in two parts; the 'flare' and the 'tube';

    The main job of the flare is to spread the low pressure zone over the largest possible area - to reduce local pressure reduction - whilst guiding incoming air into the tube with minimum disruption or induced vortices. The flare should be shaped to encourage air to enter from the sides, but not from the rear, of the mouth. This is achieved by either finishing the mouth with a sharp edge when the arc is a little beyond 90 degrees from the air horn axis or by folding material back, parallel to the axis, when the arc is at, or just below, 90 degrees to the axis.

    The main job of the tube is to accelerate the airflow smoothly and progressively. This is best achieved by an exponential shape - i.e. one where the radius of curvature is increasing constantly until the angle of the sides matches the next part of the system, usually the throttle body. At the intake end this should blend smoothly with the flare. "

    Maybe in our situation a full radius would help... but remember our trumpets are in a small box and the masking extends around the trumpet curtain area as well!

    Does anyone have any supporting evidence for what constitutes "sufficient distance"? As far as my current testing shows, there isn't in our application. It would be interesting to see what a full radius would do.. but to be honest, who cares.. the short trumpets work!

    BTW.. The 16mm trumpets I used were selected because that was all that were available to me without fabricating ones from scratch. If anyone wants to provide me alternative trumpets, in whatever shape and size, I will arrange to test them at my expense.

    Jan,

    ...If you had to venture a guess, would you deduct from your HP vs AFR graph that the power jet is coming online @ approx 4500 RPM?? That is where you really start to go rich...

    I also believe that the emulsion tubes need to be factored into this equation. The richness could well be changes in the mixture strength discharged through the emulsion tube as it reaches its upper limits.

  2. 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

  3. The Cosworth Sierra plenum was similar in that the trumpets were close to the plenum wall. Looking at the photos of the Lotus, I would say that the area around the trumpet and out to the plenum, the curtain area, is about the same as the trumpet cross-section so shouldn't be a restriction. The wave reflection is usually just outside the trumpet but it may actually be at the plenum wall in this case and so the tuning peaks don't move as much as you would expect when the trumpet lengths change.

    The rule of thumb I have always believed is that the distance from a trumpet to any airbox face or other should be at least the diameter of the trumpet.. therefore 45mm not 16mm in this case. Perhaps the curtain area does set the minimum, however if you look at the relationship of the OE trumpets to each other and to the sides of the plenum, there is very little clearance all around.

    I never thought the OE lotus S3T setup was well thought out... it seems to bear out.

    As to reflections and harmonics in the intake system, I think OE intake length is too short to make good use of anything within the rpm range of the engine. Shortening the trumpets 30mm may move any harmonic up perhaps 500 rpm. Such harmonic, as far as I can figure, would be up around 6K rpm and pretty weak.

  4. Jan,

    My car now weighs in @ 1980 lbs. VERY COOL.. I HAD ESTIMATED THAT I COULD GET MY PROJECT CAR DOWN TO ABOUT 21-2200, BUT 1980 IS FANTASTIC.. WHATS THE SECRET?

    but I'm not sure it should allow that much advance. I'm really confused on this one. Someday I might have a chance to get the car on a dyno, but there are no chassis dynos within 150 miles of here. I KNOW MORE THAN 19 DEGREES ADVANCE WILL GIVE ME MORE POWER BUT ALMOST DOUBLE SEEMS UNREAL WITHOUT CAUSING GRIEF. I QUESTIONED ZENSPORT ABOUT ADVANCE AND THEY SAID THAT TUNER ENGINES WITH ABOUT 15-18PSI BOOST RUN ABOUT 24 DEGREES AT PEAK TORQUE (WITH KNOCK DETECTION MIND YOU) .. WE WILL TRY MORE TIMING ON OUR NEXT SESSION.

    I will certainly seek a source of 16 mm trumpets! My cam sprockets are still in the stock location for my car so nothing has changed there. :fun: APPARENTLY THE 2.2 HAS THE SAME BORE, STROKE, ROD LENGTH CONFIGURATION AS A 283 CHEVY .. I HAVE A V8 TUNER FRIEND THAT SAYS THE OE CAM TIMING IS NOT GOOD FOR TAKING ADVANCE OR DEVELOPING DECENT HP.. HE GOT ALL DETAILED ABOUT THE EFFECT OF DIFFERENT MOP AND LOBE CENTERS WHICH I NOW FORGET. I WILL WRITE HIS IDEAS DOWN NEXT TIME I SEE HIM.

    I don't have much experience or knowledge w/ air correction jets, etc., but my WOT AFR went from approx 12.5 to approx 11- 11.5. FROM AN IDLE JET.. THAT SEEMS A LOT!

    So the change certainly affected my mixture across the range. I also found that my mileage suffered almost proportionally. I think you might want to try 56's and play w/ the air correction. I wish I knew more! I plan on keeping my stock idle jets for the time being. They work OK, but I may go up one size, as my AFR @ 80 mph is roughly 15-16. YIKES THATS LEAN!

    If you are interested, for experimentation, I may part w/ my 58's. THANKS ..WE'LL SEE WHAT THE NEXT SESSION YIELDS.. I HAVE A DECENT SELECTION OF JETS TO PLAY WITH.

    So to address your last paragraph, I believe that the idle jetting DOES significantly change the overall AFR, all else left the same. I AM GOING TO CHECK THAT OUT ON THE DYNO FOR SURE, AS I HAVE A HARD TIME BELIEVING IT COULD BE THAT SIGNIFICANT.

    It is also very interesting that the pump jets would affect the overall AFR, just as I found the idle jets did. You would think there would be more of a disconnect between all these dedicated systems. AGREED.

    If you had to venture a guess, would you deduct from your HP vs AFR graph that the power jet is coming online @ approx 4500 RPM?? That is where you really start to go rich. POSSIBLY.. BUT THAT IS A LOT OF FUEL TO DELIVER FROM A TINY NONE-DEDICATED JET... ESPECIALLY WHEN YOU SEE THE EFFECT OF AN AIR CORRECTOR CHANGE (WHICH ARE SUPPOSE TO EFFECT THE 5000RPM PLUS RANGE). IF THE ENRICHMENT ON THE GRAPH IS HIGH SPEED BLEED FROM THE PUMP JET, THEN THE AIR CORRECTOR WOULD APPEAR TO HAVE LITTLE EFFECT BY COMPARISON (FROM THE RESULTS WE HAVE SEEN FROM THE CHANGES WE MADE). IT JUST SEEMS WRONG SOMEHOW. HOWEVER, I DO HAVE TO ADMIT THAT WE HAVE HAD TO GET PRETTY RADICAL WITH AIR CORRECTORS TO GET THE HIGH SPEED AFR FLATTENED OUT.. BUT WE ARE HEADING THE RIGHT DIRECTION. IF I COULD FIND SOME SIZES OF PUMP BLEEDS TO TRY IT WOULD BE A VERY WORTHWHILE EXERCISE TO TEST THEM.

    Are you running the stock or aftermarket exhaust? I have a fairly low restriction exh. so it causes the mixture to lean out. YES, TWIN BOX: 1- MAGNAFLOW PLUS 1-BORLA, STRAIGHT THRU

    Another curiosity I've found is that running my engine lean does require more advance. This could mean high EGT, but If I reduce the timing, it tends to bog down. When I tied a map sensor in to my Electromotive to pull timing w/ boost, my engine lost so much power it was literally undriveable! APPARENTLY THAT IS THE CASE.

    This same problem also exists in two Mazda Miata's that I work on. One is a turbo, one supercharged; both are running only 5PSI boost. They both have an MSD boost retard device that pulls timing w/ boost. Obviously our cars would run fine on 5 PSI w/o pulling timing back, so why would they need it? When I first drove the turbo Miata, it felt exactly like my car w/ that damn map sensor hooked up. I simply took the vacuum line off the MSD and the car absolutely came ALIVE!!! After re-plumbing to streamline the system (incl. removal of the intercooler!) and removal of the boost retard, the car was VERY fast (for a Miata).

    When my customer got the car back he was amazed, but what did he do? he put the boost retard back on and killed the power!! Claiming that he wanted to play it safe because someone said to on a Mazda forum. SHEEP..

    I'm thinking that if you experience detonation, your power would be reduced dramatically. WE NOTICED 10 HP SPIKES DOWN ON THE HP CURVE, BUT THE DIPS COULD BE FROM ONE CYLINDER ONLY IN A DET EVENT.. YOU COULD FEEL IT IN THE SEAT OF YOUR PANTS THOUGH. WE TUNED THEM OUT WHEN WE HIT 12.5AFR .

    Am I entirely wrong in thinking this way? It seems as if the rough running, bogging down and hesitation would be just as bad. The supercharged one also has a rising rate pressure regulator, the turbo one did not. 5 PSI is 5 PSI regardless. I know that his rising rate pressure regulator is way out of spec, so why not remove it AND the boost retard device, and regain all that lost power and mileage?! THOSE MIATAS ARE INJECTED, CORRECT? I WOULD THINK THAT IF THE FUEL MAP CALLS FOR X AFR AT LOAD POINT Y THEN THE INJECTOR DUTY CYCLE WILL BE ADJUSTED ACCORDINGLY BY THE ECU. I WOULD GUESS THE REGULATOR TYPE DEPENDS ON WHETHER THE ECU CAN CORRECT FOR THE CHANGE IN RELATIVE DELIVERY PRESSURE.. I SOMEHOW DOUBT THAT THE ECU WOULD HAVE TROUBLE WITH A 5PSI CHANGE ON PERHAPS 50PSI DELIVERY PRESSURE. I WOULD EXPECT THAT STEADY FUEL PRESSURE DELIVERY WOULD BE EASIER TO MANAGE AT THE INJECTOR THO... SO I SAY LOOSE THE RISING RATE FPR AND ADD ADVANCE TIL THE POWER RETURNS

    My reason for rambling on is to illustrate the fact that factory settings can sometimes be very close to what we need to get the job done, the exception being the short trumpets! I wonder if they are there merely for the purpose of emissions control here in the states?? WHO KNOWS?? Are they the same size in the DOM/ROW cars?? Let us know! CURIOUS WHAT LENGTH THE ROW USES. MIND YOU THEY ARE ON DHLA40 AREN'T THEY? MAYBE LOTUS COULD ONLY GET 45MM LONG TRUMPETS FOR THE 45DHLA, SO SIMPLY USED THEM WITHOUT CONSIDERATION TO POWER LOSS AS LONG AS THEY PASSED EMISSIONS TESTING.

    Off now to search for those trumpets!

  5. Jan,

    Absolutely stunning results! NO KIDDING

    Where did you get the 16mm trumpets? ORIGINALLY FROM DAVE BEAN BUT I THINK THEY ONLY HAD THE ONE SET.

    My engine seems to be quite happy w/ a total of 32 degrees total advance @ 3000 rpm (12 static, 20 dynamic), dialed in on my Electromotive HPV-1. I didn't think ours would be that far apart though! I S/B detonating all over the place, but don't seem to have any problem. I'm trying to find out where I got the 32 degree figure from. I have much less weight in my car. Perhaps less load = more useable advance??? Any thoughts? MY CAR WEIGHS IN AT 2400LBS WHICH I THINK IS PRETTY DECENT..WE MUST BE PRETTY CLOSE?

    I WOULD LIKE TO ADD MORE ADVANCE, PERHAPS 24 DEGREES, BUT THINK THAT THE CAM TIMING NEEDS TO CHANGE TO BE ABLE TO DO THAT.. I STILL HAVE THE RED DOT CAM WHEELS IN PLACE.. WHAT ARE YOURS AT.

    I AM SURE THE ENGINE WOULD LOVE MORE ADVANCE BUT DONT WANT TO RISK DETONATION AT ALL AT THIS POINT. I AM AMAZED YOU CAN HANDLE 32 DEGREES.. I MAY PLAY WITH TIMING THE NEXT SESSION

    I have found that by going from a 52 to a 58 idle jet that it took the 'progression' hesitation out, however the WOT AFR went up significantly, so be careful there. Perhaps the power valve is kicking in @ 4500 rpm. Could you drop it's size down? I HAVE A 55 IDLE AND ONLY 2.5 TURNS ON THE IDLE SCREWS(FINE THREAD) I AM AT 13.9 AFR AT IDLE. 2,5 TURNS ISNT MUCH. IF I GO TO 60 I GET RID OF HESITATION BUT MILEAGE SEEMS TO SUFFER. I JUST GOT SOME RICHER IDLE AIR JETS TO PLAY WITH... THAT SHOULD HELP WITH THE RANGE I HAVE PROBLEMS WITH BETTER THAN THE BIG IDLE JET.

    I REALLY WONDER HOW MUCH THE IDLE JET EFFECTS OVERALL AFR, IF AT ALL? WITH THE AFR CHANGE WE GOT GOING FROM 1.70 TO 1.85mm MAINS (0.15mm) I CANT SEE HOW AN IDLE JET THAT INCREASES 0.06mm ON A SMALLER DIAMETER WOULD BE ENOUGH TO MAKE MUCH MORE DIFFERENCE THAN GOING FROM SAY A 1.70 MAIN TO 1.75 AT MOST. SINCE THE IDLE CIRCUIT OPERATES WITH THE THROTTLE PLATE CREATING A LOW PRESSURE OVER THE IDLE/PROG HOLES, I CANT UNDERSTAND HOW THE IDLE CIRCUIT WOULD EFFECT THE WOT AFR IF AT ALL. I CAN TELL YOU THAT THE PUMP JETS DO EFFECT OVERALL AFR. WE FOUND O.5mm INCREASE GAVE ABOUT 0.2 RICHER AFR AND QUITE A BIT ACCEL ENRICHMENT. THE "POWER JET" OR PUMP BLEED, AS I CALL IT, I BELIEVE SERVES TWO FUNCTIONS ONE TO ALLOW PUMP PRESSURE TO BYPASS THE PUMP JET ON ACCEL AND TO ALLOW FUEL TO BLEED TO THE PUMP JET AT WOT.. HOW MUCH I CANT SAY BUT IT WOULD BE AN INTERESTING EXCERCISE TO TEST IT OUT. ALL I KNOW IS THAT THERE SEEMS TO BE VERY LITTLE CHOICE IN POWER JET SIZES (NONE ACTUALLY) EVEN THO THE LOTUS BOOK SHOWS BLANK AND 110, NO ONE THAT I KNOW THAT SUPPLIES DELORTO JETS, HAS EVER KNOWN OF ANY SELECTION AVAILABLE. PERHAP LOTUS DRILLED OUT BLANK ONES

  6. Sorry folks.. Ive been away... quite the commentary...

    I am at 19 total degrees advance for one main reason and that was before we got to 12.5AFR (we were at about 13-13.5AFR) and getting detonation at spots along the peak torque range.. I have done some research and found 16-20 degrees of advance at peak boost/torque safe (without WI).. given factors like IAT and fuel. Once we get past the peak torque more can be added, but with the analog distributor it just isnt possible (as far as I can see) so I live with 19 (which is 3 degrees more than the book values for the fed spec distributor.

    Without an intercooler and the stock 40trim compressor..the IAT gets up there. We measured close to 160F on the surface of the intake tube.. 160F is the limit before bad things can happen.

    The OE trumpets sit less than 16mm from the plenum face which I thought was a bad design but figured that the blow-thru turbo setup needed to have some form of restriction to get a signal across the jets (a method I have read about for BT turbo VW and A-series mini engines) I decided to do a back to back test and honestly figured it would be unsuccessful because of that theory.. not so!! I now believe that lotus added the boost feed pipes to the carb tops to get a slightly higher pressure over the jets vs using restriction methods. Good on them if that is true!

    I am still playing with jetting trying to get 12.5AFR across the board, but the top end is still too rich at about 10.5 to 11.5AFR I have ordered some 250 and 260 air correctors to see if we can flatten it out.

    The 40hp drop off the end of the curve is the dump valve opening prematurely. We got one run where it held, and we got to 6500 before it popped. I will be changing the OE DV to something like the Hyperboost CORE DV

    I am as surprised as you all are.. the car drives just fine and pulls like a freight train. Albeit I am still working on the idle circuit. Using 55/#1 I have had good results but will be trying 55/#7 to see if I can knock the last little bit of progression hesitation out of her.

    The dyno runs were on an eddy current dyno at 10m/s load

    all numbers are uncorrected.. add 15-18% to get FW numbers.

    post-88-1193093283.gif

    This shows the plenum clearance:

    This shows the trumpet change:

    As an added bonus the turbo spools up faster and delivers slightly more average psi up up to WG opening... :getmecoat:

  7. Some of you may find this worth considering in your tuning plans..

    Just finished a dyno session with the 45mm long OE intake trumpets replaced with some 16mm stub stacks...

    Test was run on '85 S3T with the HC engine using 45DHLA; 9.5psi and 19 degrees total advance. Jetting 185M/240A

    Results came back with a 15% improvement in HP and 20% increase in torque over the entire rev range, plus, gained 500-1000 useful rpm!!!

    Discovered the OE BOV is pretty much crap at consistency and vents randomly at peak boost/rpm, dumping 40-50hp in the process. A hyperboost CORE DV with an adapter to mount the FPR, looks like a good option.

    A cam timing change from OE would aslo help improve the power more.

    Jan

  8. Damn car!

    I have just finished refurbishing my front suspension (new shocks, springs, bushes, trunnions, ball joints, wheel bearings, etc. all supplied by SJ), and have two problems:

    FRONT RIDE HEIGHT:

    According to the manual the ride height for an S3 N/A should be 150mm, measured at the front of the chassis centre box section.

    On another page of the manual, the figure qouted is 170mm.

    Either way, mine measures 200 mm!

    So, aside from being confused as to the correct ride height, which ever way you look at it, my car is sitting too high and I cannot for the life of me fathom how this can adjusted, unless of course I slacken all of the suspension pivot points, "pump" the suspension and then measure it again, before tightenining everything up again.

    .... anyone got another other ideas/ solutions?

    IT AIN'T LEVEL!

    When I bought the two years ago car, I noticed that the offisde rear sat lower than the nearside rear, which I put down to a worn offside rear spring.

    Prior therefore to refurbishing the front end, I replaced the rear shocks, springs and bushes, .... none of which seemed to cure the car's "list".

    Having completed the front end work, I've noticed that the nearside front sits higher than the offside front; i.e. the opposite "list" to the rear.

    So, as you look at the car from either the front or the rear when it on level ground, it sits at an angle rather than horizontal.

    ... does anyone have any ideas as to the cause of this and how it might be cured?

    As to ride height..ensure springs are the same rate and static length as the originals. Higher rate (if original length)=higher ride height. And it wont take much more rate to add 30mm ride height. Take the springs to a chassis shop and get them compared to the originals. Have them modified or replaced as required. I believe the OE rate for the S3 fronts are 125lbs.. or put the originals back in.

    As to level: I would trust that all the checking has been done on an absolutely flat level surface? Ensure that there is no binding in the suspension, and all the springs are seated, then do yourself a favour and take the car to a chassis shop and scale the corner weights, and balance them. No other real way to get it 100% IMO. Jan.

  9. Definitely interested in photos and any more details :whistle:

    How does the Renualt box compare with the Citroen with regard to length, and therefore position of the driveshafts ?

    I dont have any pix but Mike R has pix of his conversion..he is on this forum at times.

    The driveshafts sit about 25mm further back and the tail of the GB reguires mods to the rear parcel shelf and muffler config... also linkage assy was improved on Mikes project.

  10. How feasible would it be to fix the current inboard discs etc to the Renault box ?

    I have no choice on my project but to consider the UN1 unless I want to spend a fortune on an RBT ZF transaxle. With tuning to about 320hp.. the SM box would not last... hence my project conversion to UN1

    The SM box output flanges are about 75mm wider than the UN1.. I decided that the OE IB brakes were not going to work well, so on my conversion to a UN1 I have conceptualized an inboard brake system to match the UN1 using aftermarket components. That way I can retain the wheel assy and links. The drive shafts need to be longer for the UN1. Mid 80's BMW 5 series shafts are the ones to use, unless you get custom ones made.

    I have all the conversion parts in hand, and have Mike Rodriques on this forum to thank for all his valuable input.

  11. The Goodyear Eagle GT II are the right size, but unforunately only available in an SR rating.

    Jan could probably round up a set of Dunlop 8000's in 205/55/15 ZR and 245/50/15 ZR If he is prepared to hunt around as a few places still have some stock of these now discontinued tyres..

    I got mine that way, the fronts came up from the USA via ebay and the rears were in stock at a Tyre shop in London Ontario. I had them UPSed to my place and I mounted and ballanced them myself.

    You just cant expect to wander into your local Dunlop tyre outlet and pick them up anymore. :whistle:

    thx Wayne.. Ill check around J

  12. I wouldn't go against what Lotus are pushing. They spent a large amount of money and had their test drivers over every type of surface testing which available tyres would be best suited to replace the now 'out of stock' sizes.

    Did Lotus happen to recommend any particular tire brand and model as a 'best' alternative from this exhaustive testing?

    ---------

    As of 2007, I honestly believe we have little choice in size, but much in brands and compounds in a 225 size.

    I am in need of new tires now, to replace the 245/50 and 225/50 set I have. I feel that 245/50 are great for rears but 225 a bit wide for fronts. A 205 or maybe a 215 would be better IMO.. (225 fronts seem a bit road surface sensitive).

    Is there any possibility of one of the manufacturers, like Dunlop or Goodyear, being convinced to do a run for a group buy?

  13. Ok figure this one out ..I just got my 85 back on the road and the speedo needle doesnt move. If I twist the cable at the gbox end by hand the needle works.. turn the wheels, the drive works.. cable seems long enough to seat in the drive end and isnt broken anywhere.. hook it all up, but no worka speedo? Anyone ever had that problem? J

  14. Paint coatings, unless done properly can be a problem later, especially on AL, then your faced with intensive restoration of the finish.

    I use a mild solution of phosphoric acid to maintain bare aluminum. I clean up with water and may even use a mild basic solution to neutralize if needed.

    If I get lazy, I spray with a light mist of WD40 and periodically soap it off and reapply, or otherwise I just keep on top of maintaining and detailing my engine bay.

    For detailing non painted areas of the engine, such as the carbs, I use a soft paint brush wetted with lacquer thinner (gun wash) dabbed into the cracks and crevices to remove dust and oil, and use paper towels to absorb excess solvent and dirt. J

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