Motor tech talk about my dive into EFI ON A C4 VETTE TUNE PORT INJECTION

[joedrum]

Oh great pics showed up lol magic ...I didnt change the cam but I did enhance it TPI motors are lower RPM HIGH TORQUE motors so changing to aggressive cams for high rpm doesn't pay off that well mismatch to intake system ..in the pics you can see a mix of roller rockers and stock ball and socket rockers ..the roller rockers are 1.8 on the intake valve ..and th stock rockers are 1.5 exhaust ..this means the intake valve has more lift and duration and actually opens quicker too ..I did some piston knotching to make the faster moving valve didn't catch up with the piston ...it boosted the about 90/1000th to right at .500 LIFT ...on the exhaust after headers and free flowing exhaust ..that's all the exhaust needed so stock valve rockers were used
So this does change the cam in a more gentle way
.as it seems to idle pretty well ..purely a joedrum.move ..most think you are crazy to use 1.8 ROCKERS and I foundd some really cheap ...I bought two sets lol...

 

[joedrum]

I am going to do a plug check soon. ...to how how good new distributor is firing the plugs ...maybe make adjustments in plug gap ...

 

[Denver]

Funny how you started playing with Corvett's.
While i have a couple Jaguar XJ8's to play with.
They are both the early almost all aluminum cars, 04,& 07.
Back when Ford still owned Jaguar, Land Rover.
Also many of the other European auto brands.
Both needed suspension work, typical.
Both under a hundred thousand miles, still in decent shape.
Ford parts interchange quite a lot.
That along with my labor, makes them affordable dailey drivers.
Still have the Wings in the back of the garage, staying warm & dry.
Hoping i get back to riding them, again this year.

 

[joedrum]

Yes Denver hooch has been sidelined also lol but it ran went parked
So as my c4 has highly modded biggest jump is fuel injector bump.from 22 lbs.to 36lbs. The computer now is in open loop on a fuel map and ignition curve set up cold start running much like a cjoke works on carbs and for 22lbs.injectors ...well by stroke of luck engineering my c4 VETTES came with adjustable TPS sensor.stock setting of this is totally meter reading tech that totally useless in extreme modded TPI build ....
Now the joedrum caveman tech tuning tech .
How do you adjust fuel map...to tune in your big injectors ..basically a TPS sensor is a voltage regulator ..when is turned to a spot it sends voltage signal to computer from idle position to where throttle pushed to..very reliable tech.this signal can adjust the fuel map to increase or decrease injector time open for feeding fuel ..
This TPI sensor has simple slotted adjustment ...you can adjust the arch of contact with throttle plate shortest arch to longest arch .making a user friendly fuel map adjustment ..now that was a good thing the day I realized in my head this would work
With my huge injectors I pretty maxed out longest arch ...this makes the fuel come much slower rate than on ignition SBC built in ignition curve...
I am amazing myself on how user friendly I've been able to figure out ...going into black hole of totally user unfriendly routines of silicone valley machinics LOL.
My opinion on bigger injectors is rather good ..they can run on lower pressure and operate at a smaller duty cycle and can be dial in ..by adjusting TPS...
This car is already to me a joedrum success it represnets the best muscle car I've ever put together. A real front engine convertible sports car with a v8 motor and the best manual transmission ever used in a car ...the car has has not seen one minute of silicon valley mechanic or methods use to get where I am at

 

[mcgovern61]

Yes Denver hooch has been sidelined also lol but it ran went parked.

Joe, you know that is what all PO's say! (Of course we know Hooch was running when parked, but...)

 

[joedrum]

Hooch will not ever be sold lol

 

[joedrum]

I just got back fro a ride ...the outcome was great ...the car is not the fastest setup ..but it runs on 87 grade fuel ...runs in the 150 degree range on motor ...compression is on the lower side maybe 8.5 ...this about cures any pinging or knock issues...very safe motor set up ..requiring very few sensors to control ignition and fuel metering ..supper breathing head and intake manifold along with great exhaust flow evacuation ...I did no programming on computer or chip burning still has stock 89 vette chip ...I did unplug the cooling temp sensor that signals the ECM to go onto close loop running using all the sensors they came with oh another outcome of unpluging temp switch is the cooling fan runs all the time sheesh I think that's great .
Another mod I made to cooling system is a more joedrum type deal ...there is no thermostat used in this car either ...and I also use alcohol as antifreeze ..it's the best cooling fuel out out there ..it's only drawback is it boils away at 175 degrees so far I have not lost any alcohol in cooling system in several months of use ...
Performance review ...motor seems very strong for a low compression set up with stock dish pistons and bigger combustion chamber VORTEC heads 64CC over stock heads of 58CC and crappy AIR flow ...The first performace 30 % bigger intake. Moves toque curve up in RPM ..making for way smoother power band that get higher in the RPM ZONE ...it will bury the tach but shifting seems great at about 5500 to 5800 RPM IS LIKE THE SWEETSPOT ...it's probably a easy 12 second car in the 1/4 mile but I don't plan on drag racing it to find out ...
It's always great to get a non runner project going and running better than it ever has before next project is getting my 87 auto set up better and more like the 89 basically has all the same parts and have a distributor for it also right now the 87 has t small injectors and run in both loops open a closed that all changing

 

[joedrum]

It's amazing the things you can figure out ...my dive into EFI THROUGH THE C4 TPI VETTS HAS BEEN FUSTRAITING ...mostly by all the bad info out there ...and not much on real info from people with smart hands ...as it was in the oldwing world so it is with the c4 vette world ...slanted bad towards ignorance and only one politically correct way of doing something ..all others discounted ..
I've gotten to the point I've got it figured out ....on my TPI EFI from the eighties .
I general the c4 vettes TPI as sold were about having low HP HIGH TORQUE MOTOR to satisfy EPA commuist ...kind of like laying in a hospital hooked up to all kinds of machines and sensors ...to evaluate ...the computers were basically slower than today stuff ..also finicky about all things working as should ...especially when motor is not stock ...
Sheesh my motor is no where close to stock ..
Nothing applies ...to it as far as operating and working on it ...
So now I made my own variance of dialing it in ..
In a lot of ways it's easier than carb and timing ...of old school tech as the basic set up ties ignition timing and fuel timing together ... The throttle position sensor and mass air flow sensor sends signals to computer for air flow and TPS sends throttle position plate position ...this in turn tells computer much time fuel injectors are open ...
Not much you can do with mass air flow sensor ..but the TPS CAN BE MADE ADJUSTABLE WITH SOME MODDING....THIS IS MY NEXT MOD ...
It's amazing how sensitive this sensor is ....I messed with it today to get more adjustability out of it the move made for even finer tuning ..
It's funny I read all the time people saying get rid of the TPI VETT INTAKE ...put on something else ...they completely fall on there face at 4500 rpm and considered very slow ....this tells me Chevy never really had this set up dial in ...they good off the line power but we're quickly overtaken by higher RPM set ups ...but wjat if you can get to higher RPM running and keep off the line torque....this is wear I am at big time ...
It's a Great place to be and know you have built a fantastic example of instantious power that doesn't give up ...I will posts some pics after I mod the ADJUSTABLE TPS

 

[Rednaxs60]

Interesting read as always. Having spent time since October trying to get my new ECU working, have had the engine operating with the new ECU, understand a lot of your issues; however, I will mention that you may be quickly coming to a point where you will have to get into that "Black" box (ECU), and start looking at the tune. Larger injectors can be a benefit, but the injector latency (open and closing time) is set in stone in the ECU - setting(s) are probably close enough. TPS adjustment is not going to go too far depending on the fuel mapping. Could be Speed Density (SD - MAP based), TPS Based, or Alpha-N mix of SD and TPS. Use SD - MAP based fuelling at the lower RPM, then transition to a TPS based fuelling in the higher RPM because the MAP sensor signal is maxed out. Thinking this is how Honda designed the CFI system for my '85.

A lot of my issues with not being as far along as I would like to be is the understanding of the issues I have been having, an understanding of the tuning basics, and me - just learning. Trying to get 2x2=4 when every now and then getting 5 throws a wrench into the mix.

Keep at it, if it were easy everyone would do it!

 

[joedrum]

Very good points Rednaxs60 ..I think the vette ECU is at higher grade than oldwing Blackboard ..
The vette uses MAF sensor ..it will pass more air than my heads can and they are the best for SBC ...SD SET UP I jUST don't have or want ...the MAF and TPS send signals to ECU that can change fuel injector time open to fuel motor ...the TPS mod I did probably the easiest mod ove ever done ...and the impact was huge ..the greatest thing about the C4 VETTES is the are a mix of old school and new school ...of one is talented enough between old school blended computer distributor and TPS modded adjustment you can have complete control in dial it in ..if parts are capable ....if you have a burned on ability like I have setting motors to run hard and put out the most power and apply that is the art dialing in ...EFI ...CARB ...DIESIL ..OT MAKES NO DIFFERENCE THERES ALWAYS THE SWEET SPOT ...THE C4 VETTES have an easy double the power thing going on and double the lifetime also ...I must say I fumble my way to this reality ...I had no clue at first ...
Gots some new mods going on now to my 87 auto convertible vette ...if I am on track should make huge power jump when done ...just love caveman tech it can be hard to beat LOL