95' Junker Drag Truck

Glad to hear you got it up and running! :rockwoot: Hopefully I can get some free time to get mine finished up soon.
 
I bumped the timing last night from stock 12.3* to 24.5*. On the street it feels like it softened the bottom end a little in the 1800 to 2200 rpm range. The truck starts just fine but it does crank/turn over slower. Almost like the difference between a fully charged battery and a 1/2 charged battery. It will almost stall the starter but it still fires right up.

I popped the truck into neutral and it free revs to 3850 rpm. No popping or missing on the way to 3850 but I kinda thought these 4k governor springs would fuel to about 3800 and free rev to 4000. This trucks current configuration doesn't need fueling above 2600 rpm so it's fine for now.


Next step on the 95' Junker Buildup: Pressure test the lift pump pressure, delete the prescreen and fuel heater, and stretch or shim the overflow valve.
 
nice build i just picked up my 94 12v auto for 3700 (she is in a lil better shape)
P1010810.jpg
hopeing to get her into the 11's =D
 
Big Blue24 said:
I bumped the timing last night from stock 12.3* to 24.5*. On the street it feels like it softened the bottom end a little in the 1800 to 2200 rpm range. The truck starts just fine but it does crank/turn over slower. Almost like the difference between a fully charged battery and a 1/2 charged battery. It will almost stall the starter but it still fires right up.

I popped the truck into neutral and it free revs to 3850 rpm. No popping or missing on the way to 3850 but I kinda thought these 4k governor springs would fuel to about 3800 and free rev to 4000. This trucks current configuration doesn't need fueling above 2600 rpm so it's fine for now.


Next step on the 95' Junker Buildup: Pressure test the lift pump pressure, delete the prescreen and fuel heater, and stretch or shim the overflow valve.
Click to expand...

Do you plan to take it to the strip again soon? I'd be really interested to see what impact your huge timing bump has before you change any other variables.
 
Next Friday Apr 30 is Midnight Mayhem street legal drag night. I plan to make a few passes that night.

I have delivery valves and injectors begging to be installed, we'll see if I can wait.....
 
I made it to the track tonight. My best ET with the 95' Junker improved to 15.194.

My 60' time got a little better with a 2.17 on my first pass.

My best MPH was 87.45 which calculates out to 10 additional rear HP from my timing bump up to 24*. There was also a constant 20mph headwind tonight so it's probable that my truck really gained 15-20 HP from the timing bump.
 
With a bit more practice to get the 60' time down and no changes to the truck I think 14s would be easy.

Does this thing still have an open diff? I'm guessing you're spinning pretty bad coming out of the hole?

EDIT: I forgot to mention, it's looking good so far!
 
I permanently locked the rear-end with a Chicago Electric Flux-Core Locker.

My first pass had the best 60' time and I didn't spin, just pedaled it a little for the first 30' or so. I'll bet the track would have held 2.0 if I would have launched a touch harder and went WOT at launch instead of 80% throttle.

After waiting several hours for the track to clean up a ricer blown engine that oiled down the whole track, (idiot never pulled over just coasted down the groove leaving a 1/2 mile oil slick) I couldn't get it to hold more than 2.27 60'. It had a controlled spin for the first 20-25' on my last two runs.


Although the slow progressive testing has been fun, I wanna go fast! Time to install some of my fueling upgrades.
 
Nice I like the build very much, budget building right up my alley. People fall over when they hear what I have in my builds, its all in how much time u spend shopping around.

Have u swapped in the he351 yet? I'll be following this thread for sure.
 
On my first pass with the best 60' time of 2.17, I was manually shifting from 2 to D but went too far and bumped it into Neutral. That ended in a poor 10.40 - 1/8th @ 64.1 mph.

On my second pass, after the track had been oiled down, and running the whole way in D letting the truck shift on its own:

2.278 - 60'
6.257 - 330'
9.645 - 1/8th @ 72.01 MPH
12.628 - 1000'
15.194 - 1/4 @ 87.21 MPH

There was an honest 20 MPH headwind with gusts of probably 25-30 mph. I have no idea if the wind effect is negligible at 87mph but I'm sure I'll have more mods before my next drag strip passes so 10 HP is all I can prove from the timing bump from stock 12.3* to 24*.

On my 3rd and final pass:

2.361 - 60'
6.424 - 330'
9.832 - 1/8th @ 71.66
12.819 - 1000'
15.381 - 1/4 @ 87.45 MPH.




I'm still running the stock turbo with the wastegate boost reference line disconnected. It's making about 32psi in 1st, 2nd, and 3rd and about 35psi in overdrive.

I do have a spare HE351cw and a HE351ve variable geometry turbo that I've been contemplating on installing. I'm still not sure if I'm going to play around with them or just go straight to building my He351cw over HT4B compound setup.

My next fueling upgrades will be Mack rack plug, DDP magic delivery valves 024's, and unknown origin used 5x.018 injectors that I bought from Jerrod Glover here on Comp D.
 
Update:

Tonight I installed my DDP Magic Delivery valves (024) and pulled out the stock 131 DV's.

First test drive I blew off an intercooler boot, hmm.... must be making a little more boost.

After cleaning the boots and clamps, I reinstalled and went for another drive. If the timing bump was good for 10-15 HP, these DV's added another 40-50HP on top of that. It smokes just a little on the bottom end but truck ran almost perfectly clean before.

Boost is up 5psi-6psi and it now makes 41 psi in overdrive on the freeway WOT.

Remember, this truck still has tiny 160hp stock injectors. I've got a feeling this is going to be one fun project truck when i get the air upgrades built and add the 5x.018 injectors and Mack rack plug.
 
sick build man im jealous i once had a project 12 valve but i had to sell it to put a down payment on a house.......:doh:
 
hook your wastegate back up. you'll benefit more from the increased exhaust flow. 41psi is out of the compressor map and just making hot air.

Garrett
 
SSpeeDEMONSS said:
hook your wastegate back up. you'll benefit more from the increased exhaust flow. 41psi is out of the compressor map and just making hot air.

Garrett
Click to expand...


41psi is just hot air huh...... I'll bet that if I reconnected the stock wastegate setup, this truck would struggle to run 16 flat.

If you want your turbo to last a long time, you should limit boost on a HX35 to about 35-38psi. On a "Junker Drag Truck" that sees less than 25 miles per week, I think it will be just fine at 41psi.

For those wondering, the stock wastegate setup only vents the rear 3 cylinders causing a huge drive pressure spike and uneven load on the front three.

Besides that, the stock puck starts to float around 40 psi of boost from drive pressure overcoming the spring pre-load in the wastegate actuator. If anything, I'd go in and drill the divider to even the pressure on both volutes.

If you'd like, I can make a pass with the wastegate connected at the stock 19.5ish psi and then make another pass at 41psi to demonstrate the difference.


Contrary to popular belief, a turbo will flow more air the faster it is driven all the way till mechanical failure when the compressor wheel flys apart. It's true that efficiency drops off quickly when pushed "off the map" but flow does still increase. The expense of reduced efficiency is it requires a lot of extra shaft HP to spin the compressor. This extra shaft HP comes from higher drive pressure and exhaust temperature. Higher drive pressure does steal HP from the motor but in my experience, the point at which rising drive pressure steals more HP than the extra compressor flow creates is never met before the turbo fails.

I have not tested a large single or compound turbos so i can't really say how they react to higher drive pressure.

I will tell you this, I know without a doubt that on a stock head/cam/valved 12valve engine, an HX35 will make more power 50psi than it will at 20, 30, or even the magical 35psi.
 
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