t-na bottom end
Been ages since ive posted on here but i too did a write up years ago on a 740turbo that i built. So i will give a huge post of my experiences.. I went a waaay different direction in my na-t though.. I had a turbo car(1990 744t) with turbo ecu-i wanted a na block -more compression , more power! I bought a used b230f out of a salvage yard for $100 ,125k on it, used the turbo head (sodium valves.. not really an issue) a supra fuel pump in tank (mk3 turbo) and supra mk3 fuel injectors. I had supra parts laying around everywhere! I bypassed the injector resistor by jumpering it back to itself. I used a radio shack potentiometer on the signal wire from the airmass meter to the ecu and adjusted my airfuel with the potentiometer.. It was a $2.25 air fuel controller, why use safc? Your 02 sensor adjusts for idle and part throttle mode, and the amm takes over when the boost hits the fan.
Anyone who has tuned a car knows that part throttle is usually the most difficult to tune-this is where the lh2.4 shines and adapts amazingly well to large mods-this is already tuned for you thru slowly running your car thru it paces. All i adjusted for(with pot) was for part to wot.Because of the 440 cc supra injectors the hardest part of this whole project was the first initial start up, the o2 sensor wanted to see less injector than what i had in it. It kept flooding it! It took about 10 minutes (no ****) to start the car, then the ecu learned over it and it worked great from there. I bolted a turbo oil return line upside down into the top of the oil pan and used ss hose and a turbo return line gasket (because thats all i had at the time). A friend of mine ,Jack Harris had a shop in Nc and offered to dyno my car when i drove it from Tx to NC and back to Tx. He had questioned the validity of my potentiometer and its relevance to my application. We strapped it up on his dyno (mustang ) at p1 auto (his shop) . I had g-teched it earlier at 327whp , but doubted that ..Even though i pulled my moms vette in Va..So we strapped it up and turned the pot to wide open(hardly any resistance). Car wouldnt rev past 3500 and was waaay rich. Then turned it down to the setting i liked and the airfuel drastically changed. If i remember correctly it made 195 wheel i believe with the turbo falling off and 235 ft pound on a na motor (big rod).
I posted up details of all this maybe 5-8 years ago.Then forgot my password and had to change username.
I noticed on the drive back the car was getting slower and slower, then i saw the turbo was loose. I remember being disappointed at the dyno runs !
I don't know where the heck the post went, i even included the air fuel change on the dyno along with the runs..It works but you have to have a clue as to what you are doing. I always ran 93 octance and when i knew i was gonna beat on it i would add two cans of Berrymans B-12 (it has toluene as main ingredient which was the f1 fuel of choice in turbo era where 91 ci motors in the back of the line where making 1100hp-also used in TNT!) which is also great for cleaning stains off concrete and melting bees!
I haven't seen anyone mention this thru-out this whole thread, so i will make it Known.. If you plan to beat on your car for more than 20 seconds continuously, like say doing a top speed run down a highway with your buddys b-16a bottle fed hatch , for a hour or so on and off, be prepared to pull over and call a tow truck.. You will melt the motor if you stay in it for way too long , and don't ever allow the intercooler and turbo and motor to cool down..Have common sense..I apparently didn't have any , so i learned me some sense! That was my own mistake for melting it but it ran with that same setup for a few years. had i not been a jackass, that motor would still be kicking..
I also used a turbo off of an merkur xr4ti that i found in a salvage yard..After i got back to Tx i put an npr intercooler on it and ran it at Kennedale 1/8th mile track. It ran a 9.0 with a 2.1 60 foot (1 tire fire) and broke the trans on the second boost launch of the night..It was a fun car. I sold it when i left Texas with a 16valve stuffed in it with a regal turbo welded on a fabbed down pipe off the stock exhaust manifold, divorce sucks in the middle of a big project..
Fast forward, Did the same list of mods to a friends 92 940 turbo, BUT -SMALL rod na block w squirters, merkur xr4ti turbo, potentiometer WIThOUT the supra injectors (he never would put them in -i told him the pot is pointless without larger injectors) and he added a huge front mount intercooler to it, i mean it was freakin massive, he cut the front bumper supports out -had to move headlights and all kinds of Nonsense to get this intercooler to fit when i was working at Alamo Autosports. I told him to keep the boost down, so he kept it down for a month,10psi- then cranked it to 20 and beat the living daylights out of this 940, turbo kept comeing loose , intercooler pipes keep blowing off and splitting hoses. But he road raced it at TMS and daily drove the car and was always doing 1/4 mile burnouts with it... Apparently Lucky at Ipd and he, had some great plans for this car-but they didnt pan out due to financial restraints..ANYWAY,That car was amazingly faster than my 740 with comparable mods, less the giant intercooler he had-psi per psi. Plus he was able to run 20 psi w/o hitting fuel cut. i could only run 13-with 15 psi initial spike. Moral of the story is if you go na to turbo, the lh2.4 i think- is most forgiving. That's why i now have a 1993 945 t with a na bottom end in it with smaller rods.. It makes more power pound for pound, but over all may not be able to handle as much power as a thick rod motor -say a b23ft. The volvo red blocks, each one in its own respect is tough as nails. But- tuning, common sense, and preventive maintenance is everything! Anyone can blow up any turbo motor if they keep their foot in it long enough. Keep that in mind!
End short story.
Kris Weldy
My current turbo car orig, with a na bottom end , slotted "A" cam and oversize exhaust Valves that KNox did the headwork on , And Vince Ported.
http://www.facebook.com/kris.d.weldy?v=app_2392950137&ref=profile#!/video/video.php?v=1231631602478