Finally after 3 years waiting we hit the RotoTest dyno with our 13B PP dragrace car. Some short specs 9:4 cr rotors. RA 2 mm apex seals, 5 pin doweled,Gene Berg 54 mm IDA carb,short 50 mm primaries,Pro Spark sequential ignition and finally the 3rd spark plug FT (Far Trailing) ala Mazda Le Mans 4 rotor engine. The 3rd sparkplug is controlled by a DIS4 and a Megasquirt box at this early prototype stages. First test was to idle at 2k at lambda 1 then switching to 3rd FT plug. Observations were that idle went down to 1.5k stumbling and lambda goes up to 1.25-1.35Proof that it ignites the lean mixture in the squish. Next test was a static dyno run for 5s at 7.5k, first with 2 plugs and ignition L 20deg T16 deg. Power was 211 hp at hub.Lambda at 0.90. Then connected the FT + wire and tested again... 220 at hubLambda went a litttle bit leaner at 0-92-0.94 but was not rejetted due to lack of time. We had big troubles with ignition wires that were to low in resistance, but then switched to 10kohms wires, problem solved Spark plugs thenWe use new BUR9EQ in all 3 holes per chamber. The ideal timing for the ignition timing for the FT plug has to be more in depth dyno tested. Finally we did a dynamic 10s run from 5500 to 10 000 rpm. The engine made 295 hp at 9186 rpm according to RotoTest Datmon log ( i lifted the pedal becausse i could hear some small misfires) Now we shall compete in a dragrace event at Kjula Raceway on 30-31/5 Hope to see some 10s time slips from our 800 kg (1765 lbs)Mazda RX-4

/Lasse

 

did you play with split at all?
The only real way to test and see if the far trailing plug is giving a gain would be to tune it with just two till you hit peak then use the far trailing and start all over again. Not trying to shoot down your work just trying to get a feel if you got 9 HP from the extra plug or just the extra split / sparking power. What ignition setup are you running for leading? On my old BP I had a loss of only 3 HP *256 ->253* to the ground removing the trailing when using one CDI box and coil per leading plug and had little change with more or less split.

 

First off, cool info. The last two Sevenstock events that I went too, there was a booth and I forgot what the booth name was, but anyway they were selling the third spark plug housings, or they would drill your own housings. I don't see a big gain in horsepower from doing this. I think the main reason why Mazda did it to the 4 rotor was to squeeze some more fuel economy out of the engine for the Le Mons race. But I guess when racing N/A, every little hosepower helps. Looking forward to seeing further tests and results.

 

Good ideaI don't know when we have time to dyno more but it will be this summer. We run 20 deg L. Didn't tune any more becausse of lack of time. I have seen up to 10 hp more power when adding 1 deg on a PP 13B i built.Also my experience showed that zero split is best for our Rallycross PP engines. This was on a Stuska engine dyno. We use sequential ignition with 4 MSD trafo type low ohm coils. Spark wires are 10k Ohm. Waiting now for our first dragrace this year, shall be funny

/Lasse

 

Cool project! Keep us informed.

 

Hey I forgot to ask. How the heck did you get an RX-4 down to 1700lbs?

 

The chassie is still steel stock profile but has been replaced with 1 mm alumina floor. Back halfed with light weight tube front suspension, 25 lbs glas fibre flip front,no innerwalls, engine 3" backward mounted with alumina front fire wall,All glass windows,rear trunk lid glassfibre,carbon fibre 500 grams rear bumper alumina rear wing,Centerline wheels with motorcycle front rims, G-Force tranny, 9" with alumina spool and lightened drums, 2 gallon fuel tank min stainless one JAZ seat with full alumina interior and 10 point roll cage and many more things i can't remember now.Mikael has owned the car since 1987! And built it in 3 steps. W shall weight it on a good car scale this summer, but we have weight it to 1545 lbs on a truck scale (not exact) without Mikael in it last summer. I have pictures but i,m lazy as hell as posting them, but will do! Now i'm heading for a dyno session with a 13B PP rallycross engine today.

/Lasse

 

Awesome project!! Its great to see someone trying the third spark plug. No one tries it after they hear it doesn't make huge gains in power.

Since I don't know a whole lot on tuning a rotary (ignition timing), I'll only say be sure you've got the motor tuned for all its worth on two plugs so you know EXACTLY how much you've gained as you tune it with the third.

Looking forward to future results!

 

Very interesting testing. Would be nice to see what kind of gain is seen all around the rpm range though

 

thanks for not taking that the wrong way. I had a unique set up so i don't know how my GDI changed the usefulness of split. I assume your running fixed? it sounds that way, I was running fixed as well at 20 with a spit of 9. but as i said I don't know how the GDI would effect the usefulness of the trailing plugs.
Hope you get some dyno time soon to get some good info out there, I wish you the best of luck with the setup.

 

FWIW: The gains from this shouldn't be much. The 26B engine picked up between 1-3% in economy and torque depending on rpm and keep in mind it was all up high. Let's say you have a 300 hp engine. That's between 3 and 9hp gained assuming it all works correctly. It probably won't be a feelable gain. The average street engine would only gain roughly 2-5hp from this. Nothing you'd feel.

Obviously in racing every little bit counts and may be worthwhile on a race engine but I seriously doubt it's anything worth pursuing if people are just going to build street engines. It is cool to see someone playing with it though and the results will be interesting. You can never learn too much.

 

Sounds awesome. Post some pics when you get a chance please. And what is the best 1/4mile time? Any vids?


See post #3. Repost. LOL

 

First a question, what is GDI? We run 20L and 16T and 12FT. I have seen most max hp of no split on my PP engines both with dizzy w/MSD6A and sequential programming direct fire such as ProSpark. More dyno time will come in early July i hope, forst we shall compete in some races I have a new built PP 13B on Super flow dyno yesterday with some 2 mm later closing of the intake (still D shape). We only made 281 hp STP corrected@9000 rpm but with small 45 mm venturies in the 54 mm Gene Berg carb. The plugs is to cold for this output (BUR9EQ),they were a little dull black and i like to see gray or a little bit white color.Ignition was 20L 16T up to 7500 rpm then raised to 22L 18T, that picked up almost 10 hp.
On Monday further testing is to be made with bigger venturies from 47-49mm and re jetting the carb. I use Shell V_Power 99 octane fuel but will be testing E85 also if time permits I hope this engine shall make a little bit of 300 hp@9000 rpm or more, but we will see...

/Lasse

 

Yes that,s correct, we only made 3-4 more % hp wise but without maximising the 2 plug set up first We switched to R11.5 and lose hp but the 4 trailing plugs looked great in color! Ignition timing,split and the heat range of the plugs all that is to take in concern when you dyno, it's a complicated world

/Lasse

 

[QUOTE=ultimatejay;9226005]Sounds awesome. Post some pics when you get a chance please. And what is the best 1/4mile time? Any vids?

Thank's! Best ET 2002 11.42s-120 mph. 60ft 1.62s 1/8 mile 7.21s-96 mph. I have old videos that shall come up on my "new" home page this summer. Hopefully my Webmaster has some time for me...? Looking forward to next weekend when we hit the dragstrip since 2002Of course hope for 10s time slips

/Lasse

 

GDI -> gas direct injection.

 

a few pics!

 

I think we need more engine bay pictures

 

i think we all need more pics period! hot car by the way.

 

here's another picture of the car

 

Very nice metal work on the interior. Lightning holes, good hole pattern, Tranny tunnel cover wher it connects at the firewall is great too. Nice work

 

Has the top dowel pin been eliminated to fit the third spark plug?

 

I was curious about the same thing. DId you just relocate the pin or is there two smaller pins on either side of the plug or something else?

 

Here's a vid of the car, you can see more of the interior and engine bay

http://www.norrortracing.se/fernis/B..._by_Fernis.wmv

 

3 years for this?



totally worth it!