What is the max boost I can run

[jeffgilbert]

What is the max boost I can run on stock compression with out pulling timing? I have a mpi kit with intercooler and quick spool wast gate and I can not get the boost down even with zero pre load on the actuator I still creep up to almost 7 psi. Right now I have stock injectors but I have larger ones on the way can I run 7 psi with the larger injectors without pulling timing and running into issues or should I reinstall the original waste gate actuator? Would a manual boost controller with the original actuator work as good as the quick spool waste gate for building boost fast? I am not running the EABC because I am using the PCV-PTI.

Thanks

 

[tapex_07]

No more than 7 imo.

 

[jeffgilbert]

So you think 7 with bigger injectors is fine without pulling timing?

 

[tapex_07]

With stock injectors and stock pump. An important thing to remember is fuel quality also...

 

[TD Max]

Three questions:

1) Where does your wastegate actuator get it's "source boost"
2) Where are you reading boost pressure for your gauge?
3) Have you checked your gauge accuracy?

 

[jeffgilbert]

Three questions:

1) Where does your wastegate actuator get it's "source boost"
2) Where are you reading boost pressure for your gauge?
3) Have you checked your gauge accuracy?

1- it comes from the intercooler on the supplied nipple

2- I use the MAP sensor located on the intercooler for readings right from my PCV PTI

3- I would think the MAP sensor would be accurate but I has another Bosch one that has the same part number that came with the gemes controller I could try. I know it's over boosting because it's giving me lean AFR after I cross over the 6psi mark.


I did try both actuators with shop air @5psi and the quick spool give a much smaller stroke but looks to start to move around 3 psi. The original has a much larger stroke at 5 psi but begins to stroke almost instantly. Both with no preload set on them on the bench.

 

[TD Max]

My thought process (having zero experience with the Viper, but plenty of turbo experience) is that if you were to plumb the wastegate to a point pre intercooler it would be in the highest pressure portion and activate the earliest.

Looks like you are seeing a wastegate flow issue in that it is opening, just not far enough. Am I following correctly?

Sounds like you need to go back to the std wastegate actuator. We make a boost valve that we use to attenuate wastegate signal and adjust boost while speeding spool up. I sent a sample to Ulmer but I don't think he has tried it yet. My concern was that we could scale it low enough. It seems really broad banded in that we can use it on 20 psi and 60 psi setups with the standard spring. I lightened the spring up and think it should do well at lower boost figures.

 

[TD Max]

Also are you clutched for big RPM or are you down below 9,000?

Seems that your condition is unique and it may just be that the RPM that you are running is just driving the turbo that hard.

 

[Yamadog]

I can tell you with stick pump and injectors 7 is a risk. I am running 7.5 on stick motor with timing pulled by evo flash high flow fuel pump and 4th injector in the intercooler And still may be dealing with blown head gasket not sure what has happened yet. In 13 my 1st viper blew up badly at 6.5 #`s with Afr #`s at 10.5 @ wot while running mainly a mix of 91 pump and 110 octane.

 

[Studroes144]

I can tell you with stick pump and injectors 7 is a risk. I am running 7.5 on stick motor with timing pulled by evo flash high flow fuel pump and 4th injector in the intercooler And still may be dealing with blown head gasket not sure what has happened yet. In 13 my 1st viper blew up badly at 6.5 #`s with Afr #`s at 10.5 @ wot while running mainly a mix of 91 pump and 110 octane.

U running a quiet muffler or race can on your stock compression turbo?

 

[tapex_07]

I can tell you with stick pump and injectors 7 is a risk. I am running 7.5 on stick motor with timing pulled by evo flash high flow fuel pump and 4th injector in the intercooler And still may be dealing with blown head gasket not sure what has happened yet. In 13 my 1st viper blew up badly at 6.5 #`s with Afr #`s at 10.5 @ wot while running mainly a mix of 91 pump and 110 octane.

Valuable info right there.

 

[jeffgilbert]

I was Talking to Ulmer last night and he told me to move it to the port right on the compressor as TD Max suggested, I had forgotten that there was a port on the compressor until I looked at the mountain kit instructions and the intercooler instructions then you can see a good pic of it. Its a job to see it in the trail kit instructions. I have a set of 430cc injectors on the way so I will be installing them and try and set the boost for 6psi off the compressor to keep it safe and that way if it spikes to 7psi a few times I have the extra fuel, I do plan on doing the evo flash to pull timing next season. Yamahdog, Ulmer did mention to me last night that 7psi would be the max with stock timing but he said something that made a lot o sense, to install a relay and switch or fan controller for the rad to keep the water temp down around 165*f to stop detonation from happening when in the higher boost he said that when you are up to the point of the fan coming 93*C on and into higher boost that its too late and its already detonating with the stock timing and compression. also in the mpi instructions with talks about a similar thing such as adding extra coolers or running the fan off a switch and that's only att 4.5-5 psi trail kit.

Thanks for the help guys!

Ill let everyone know how it works when running the boost line right off the compressor.

 

[jeffgilbert]

U running a quiet muffler or race can on your stock compression turbo?

race muffler

 

[Yamadog]

After last night I can tell you I no longer believe that even 7 lbs is safe on these motors. This is the 2nd viper I have blown up in 3 yrs. This time it is not a fuel problem for sure. My 14 started having problems from day 1 after the build and was only at 5#'s of boost. I would drop a cylinder then it would come back it did that several times between 200 and 500 miles and finally blew a hole between 2 cylinders at about 560 miles. The 15 has timing pulled with EVO flash, upgraded fuel pump, 4th injector in the intercooler and had never been run in high boost because it was still in break in. Only 1 time has it been run on straight pump gas and that was for the St Germain pump gas turbo trail sled shoot out. All other times I ran 2-3 gal 110 race gas every time I filled it up. Even the races I ran are only 660' so the WOT runs were short blasts.

The last ride of last season I was enjoying a great trail ride with 2 buddies. we did about 40 miles of easy trail riding and I was bringing up the rear. We came out the woods and hit the rail grade I jumped on it and passed them went about 1/2 mile NOT at WOT just running 100 ish vs the top end at low boost of 126. and bam it limped then shut down. it took 2 hrs to get it to a road then called for a buddy to pick me up he was an hour out and I went to get lunch. I got back to the sled before he showed and started it and rode 15 miles no problem. Sat all summer and went 2 weeks ago to UP rode a bit Thursday night. Rode 20 miles Friday morning then bam it did it again. limped it back no sign of fluid does not smell hot and the fluid in the overflow bottle is cool. Radiator is hot bot not excessive and the rear heat exchanger is warm.

Since have changed thermostat and radiator cap and last night it is so bad that 2 300' rips on my lake and down she goes and now coolant on the interior of the side panel.

HEAD GASKET at a minimum!

 

[Studroes144]

After last night I can tell you I no longer believe that even 7 lbs is safe on these motors. This is the 2nd viper I have blown up in 3 yrs. This time it is not a fuel problem for sure. My 14 started having problems from day 1 after the build and was only at 5#'s of boost. I would drop a cylinder then it would come back it did that several times between 200 and 500 miles and finally blew a hole between 2 cylinders at about 560 miles. The 15 has timing pulled with EVO flash, upgraded fuel pump, 4th injector in the intercooler and had never been run in high boost because it was still in break in. Only 1 time has it been run on straight pump gas and that was for the St Germain pump gas turbo trail sled shoot out. All other times I ran 2-3 gal 110 race gas every time I filled it up. Even the races I ran are only 660' so the WOT runs were short blasts.

The last ride of last season I was enjoying a great trail ride with 2 buddies. we did about 40 miles of easy trail riding and I was bringing up the rear. We came out the woods and hit the rail grade I jumped on it and passed them went about 1/2 mile NOT at WOT just running 100 ish vs the top end at low boost of 126. and bam it limped then shut down. it took 2 hrs to get it to a road then called for a buddy to pick me up he was an hour out and I went to get lunch. I got back to the sled before he showed and started it and rode 15 miles no problem. Sat all summer and went 2 weeks ago to UP rode a bit Thursday night. Rode 20 miles Friday morning then bam it did it again. limped it back no sign of fluid does not smell hot and the fluid in the overflow bottle is cool. Radiator is hot bot not excessive and the rear heat exchanger is warm.

Since have changed thermostat and radiator cap and last night it is so bad that 2 300' rips on my lake and down she goes and now coolant on the interior of the side panel.

HEAD GASKET at a minimum!

I had a head gasket go out on mine the first year as well, never run over 6 psi. I wouldn't risk anything with a stock compression engine.