Any experience or advice on Webber IDA downdraft carbed- Mazda rotary engines showing more HP at high elevations vs sea level?
We used a full size Dyno Jet dyno used at sea level and a portable dyno Jet equivalent approved unit at elevation (4400 ft), same model weather station equipment used at both locations.
(note when we first got to high elevation location dyno we were told we had 152 HP on the tune we started with which we figure at best was a mid 145-148 HP at sea level. How can this be...? We figured we would lose some HP not gain more?
At the end of the experience after detuning several times. we were told we now had 145 HP at 4400 ft elevation, then came back to sea level, two days later, similar weather conditions mid 80's low humitity, and the same tune up produced only 137 HP. Both numbers were adjusted figures.
Questions... Is it possible to make more HP either real or on paper at elevation due to volumetric eficiency of a rotary engine.
Can the operator of the dyno put in incorrect data thus making the numbers come out incorrectly.
Please add any additional information that help us understand this problem we and many other experienced.
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Re: HP increase at elevation using a Dyno Jet Dyno?
Same dyno? same operator? theres something wrong. the lower altitude the better, as far as I know. But someone thats smarter than me and has high altitude /dyno experience would be better to answer the question.
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There is a strong relationship between Ford and Mazda with many shared designs.
Almost any engine can be fitted into any car, even some that seem physically too large. Few such conversions require no engineering and some require a great deal of engineering.
Sometimes a conversion needs no engineering and that is lucky...
I don't know how much, if any, engineering your proposed conversion will need and I suspect few people will be able to tell you with much accuracy.
The best advice I can offer is to make a careful study of the donor car and take careful measurements before deciding to go ahead and such a conversion usually is better made with the donor car on site. Whether such a conversion goes ahead really depends on the facilities available to you and your skill level and experience.
There is little point in such a conversion if the finished car is not much improved afterwards and that usually means more performance but it must be realised there is much more to a good conversion than a mere engine change. The clutch and/or transmission must be able to reliably withstand the increased torque, the brakes often must be modified and when the new engine is significantly heavier the suspension too must be modified...
An increase in power means increased cooling (a bigger radiator and fan) and there must be plenty of room for an efficient air intake and the exhaust system will probably need to be custom made. Quite probably the Mazda electronics will need to be used unless they too are to be custom items - and that can produce a whole new load of problems...
things to check will be float level, main jet size for the engine capacity, power circuit operational, accelerator pump working, ignition timing
by installing a different carby , make sure that all the holes in the carby base are not blocked off by a gasket that has no holes
I built these engine on the assembly line ,couldnt you fit a OHC cortina engine as in the UK its not a issue with the paperwork and technical engineers like it is here in spain but finding a kent 1.6 GT lump with a webber carb nowdays ? ever heard of a brown stuff from a rocking horse?
The side seals for the rotors are bad. the only thing you can do is pull the engine apart and replace the seals IF the side housings are good. If they are bad, you cant machine them, they are JUNK. Find a shop that rebuilds Mazda Rotary engines. Mazda may be the best place to get a reman engine.
easy to do reset the carbs ,their SU type and the needle jet adjustment is a 1/2 inch nut on the bottom of the carb screwing it up reduces the mixture and lowering it increases the fuel ,list when engine warm and get the hissing right to balance them ,but without experiance use a gunson colourtune spark plug and trumpet type product as well to balance the airflow ,easy to do not difficult at all dont be scared of this old beast they were dogs when new let alone now as a classic ,not a patch on the 1600E cortina even better was the sumbeam rapier
1. The accelerator pump in the carb is clogged, the linkage is unhooked, or the diaphram in the pump is bad. It's cheap to replace and comes in the carb rebuild kit. This usually just causes hesitation when you step on the gas pedal. It doesn't usually cause the engine to stop running.
2. More likely is that the main jet in the carb is clogged. At idle, high vacuum under the closed throttle plate in the carb causes fuel to flow thru the idle jet. As the throttle plate opens (as you step on the pedal), the vacuum under the plate dissipates, stopping the flow of fuel thru the idle jet, and the vacuum ABOVE the throttle plate increases, which is supposed to then draw fuel from the carb bowl thru the main jet in the carb. If the main jet is clogged with dirt, then it can idle just fine and die as soon as you step on the pedal.
Baseline would all depend on what its going on big block or small block if its a small block a 850 is too much carb. because you have to jet it down so far to get it to run right and not foul the plugs because of to much gas unless its built 650 or 750 would be the right carb for the street you can start with 70 in front and 72 in rear is a good starting point, the thing to do is get a jet kit from holley and experiment with it.
if it wont hold an idle then one or more of the cylinders are probably too low or high in compression and if it's backfireing then the ignition timming could be off. I would take a compressin test of all cylenders and if they are all in range I would hook up a timming light to se if the timming is out