98 305 Silverado help

Step-son has a 1998 C1500 Silverado that was his grandpas truck he got after his grandpa passed away. Thanks to me, he want to modify his truck to be faster. I know the best budget option would be a 5.7L with a 411 PCM swap, but being its his gpas truck, trying to keep it somewhat original, and he can get a different vehicle later on to build for performance. I recently picked up a MPVI3 to use for my Dakota R/T I am rebuilding right now, so am kind of using his truck for getting my feet wet with tuning, before trying to tackle a 410 stroker nitrous build in the Dakota.

Ive done a few small things. removed engine torque management. tweaked the MAF table a little to get LTFT a little closer to 0. increased dwell time on spark. increased shift pressure and increased shift speed. not using a wideband right now. and not trying to tune it for max performance, just a little more get up and go. He will be racing in a teen driver bracket series at local track this summer. Not sure if he will use his truck, or my Ram 1500. The changes I have made so far have helped, but feel there is more that can be done. I removed burst knock retard, but havent uploaded that tune just yet because his is at his dads house this weekend.

Attached are current tune file, and most recent data log from driving. probably need to do a bit more driving to get a better log file. Attachment 144032Attachment 144035

You could lower the power enrichment settings a little too. I'd say go with 65% throttle enable. Lower the rpm delay to 1500 or 1800rpm. Then set the whole EQ ratio to a flat value of 1.200. That will give it a safe AFR of 12.23 commanded.

It's always hard to tell from o2 readings but the longer it's in the throttle the lower the o2mv readings get. So it could be a little lean there but hard to say with a wideband. Fuel pressure could also be dropping off if the airflow model was correct.

A 305 isn't horrible but if wanted to keep it original to the truck, just doing a camshaft swap would make a good bump in horsepower/torque.

Thank you. I hadn't messed with PE because I didn't quite understand that part. I had noticed that the commanded A/F ration at WOT in hgher RPM was 11.90 at higher rpm and was trying to figure out where to adjust that leaner. Made the adjustments you suggested. Will load them tonight when the truck gets back to the house, and take it for a drive.

Quote:

---

Originally Posted by hskrRT

Thank you. I hadn't messed with PE because I didn't quite understand that part. I had noticed that the commanded A/F ration at WOT in hgher RPM was 11.90 at higher rpm and was trying to figure out where to adjust that leaner. Made the adjustments you suggested. Will load them tonight when the truck gets back to the house, and take it for a drive.

---

You can also increase the Ramp in rate to 1.0 and decrease the delay timer to 0 if you wanted to.

305s are very susceptible to spark knock on 87 octane gas, especially if you eliminate the EGR. Keep an eye on KR if you add any timing and lean out the PE. More timing with a richer PE will be better than less timing with a leaner PE. There is no real need to 0411 swap a 98 305 truck. 305s are really limited by what their heads flow.

We did do an EGR delete when we installed headers. Forgot to say i disabled the EGR in tune as well. that really was initial reason for doing the HPTuners on this truck. Have also home ported the throttle body. will upload the latest changes to PE and burst knock disabled, and see what the logs look like. I have not added any timing. Everything I have read says to get the fuel tuned first, both speed density and MAF, before messing with timing.

Quote:

---

Originally Posted by hskrRT

We did do an EGR delete when we installed headers. Forgot to say i disabled the EGR in tune as well. that really was initial reason for doing the HPTuners on this truck. Have also home ported the throttle body. will upload the latest changes to PE and burst knock disabled, and see what the logs look like. I have not added any timing. Everything I have read says to get the fuel tuned first, both speed density and MAF, before messing with timing.

---

yeah, that's usually the process, Fuel, Air, Spark, Transmission, Torque management.

Quote:

---

Originally Posted by 5FDP

You could lower the power enrichment settings a little too. I'd say go with 65% throttle enable. Lower the rpm delay to 1500 or 1800rpm. Then set the whole EQ ratio to a flat value of 1.200. That will give it a safe AFR of 12.23 commanded.

It's always hard to tell from o2 readings but the longer it's in the throttle the lower the o2mv readings get. So it could be a little lean there but hard to say with a wideband. Fuel pressure could also be dropping off if the airflow model was correct.

A 305 isn't horrible but if wanted to keep it original to the truck, just doing a camshaft swap would make a good bump in horsepower/torque.

---

Made the changes, here is log file for drive afterwards. burst knock off and PE tweaks

Attachment 144098

Quote:

---

Originally Posted by 2xLS1

305s are very susceptible to spark knock on 87 octane gas, especially if you eliminate the EGR. Keep an eye on KR if you add any timing and lean out the PE. More timing with a richer PE will be better than less timing with a leaner PE. There is no real need to 0411 swap a 98 305 truck. 305s are really limited by what their heads flow.

---

Absolutely zero of that is true on a L30 Vortec.

The factory L30 heads flow better than the Mexican L31 Vortecs GM has been selling for the past 20 years. The L30 heads make max power around 29-30* total timing and are not at all susceptible to spark knock on 87 from my own testing. I had a L30 head 305 at 10.4:1 compression even and never found it limited by knock, power actually fell off before I ran into knock. I also had a boat with one and those had the 7395 cam in them that boosts dynamic compression and no EGR. The marine L30 in my boat was rated 260 hp and 310 tq with the tiny 196/206 cam and it ran at 28* total timing on 87.

Generally speaking with Vortec heads on either a 305 or 350, when you start pushing them hard you need to drop from a hot 44 heat range to a cooler 43 or 42 heat range plug. My L30 boat had MR42 plugs and a 160F thermostat.

I have run about 6 different L30 305 combinations over the past 20 years. Even had one in my 97 Express for a while after I hurt the 350 spraying it with a 150 shot for a few years and was building the 383 for it. I was spraying the 305 with a 100 shot while it was in there too just to give it some etra umph at times. With MR42 plugs and the 100 shot I was running 26* total on 87.

I will also add that the nitrous was not the direct downfall of the 350 either, the oil pump pickup fell off and the engine staved for oil while being sprayed up to 6,000 rpm and it almost spun #1 rod bearing.

Well aren't you special.

Quote:

---

Originally Posted by 2xLS1

Well aren't you special.

---

Well you are regurgitating an internet myth from the days when people removed the emissions equipment on carbureted 305s. Of course they had issues running carbs and HEIs calibrated to work with EGR without it and also attempting to crank up the initial advance without limiting the vacuum advance and centrifical advances. Even those ran great if you properly recalibrated the carb and changed up the advance curves. Stock timing spec for most 305s was 0-6* initial. A lot of guys would try to run 12-16* initial advance. Some of the smog era 305 HEI distributors had 24-28* of centrifical advance in them that did not arrive until 4,000+ rpm and the soft material GM used at the time for the advance plate would wear and it would give even more as the advance curve plate wore out. Last time I checked 12 + 28 = 40 then add in 20* of vacuum advance and you get 60*. Pretty easy to figure out why the 305 got that reputation and it was not the engine itself. The problem was the guy tuning it.

The L30 305 is not even in the same ball game as those carb era 305s. The L30 is 100 Net HP up on the smog era dualjet 2bbl 305s built 1980.

GM themself even 0411 swapped the L30s, it is a better and more tuneable PCM all around. A 305 will see the same benifit running one that a 350 will.

I will even also add the SAE writeup GM wrote for both the L30 and L31 during the development and SAE dyno testing were around a few years ago. I read both. The 305 was only down ~15 hp and it had 50% more exhaust backpressure from the single catalyst exhaust system than the 350 did with even the horribly restrictive smaller 1500 dual cat exhaust on those trucks.