LQ4 with Summit 8707 cam with stock 8.1 injectors

Trying to get a head start. This is actually in a circle track race truck that I am prototyping for our racing series. I have done plenty of programming, and have been a drivability technician for years, but as far as tuning...not so much.

This is designed to be a next generation powerplant. Our rules limit us to 375HP/375TQ at the rear wheels....for the prototype it's an LQ4 out of an 05 Express van. The only modification to stock is a Summit 8707 cam and long tube race headers. No TBSS allowed, stock throttle body. We mandate cable throttle bodies for safety reasons.

The fuel system is just a sender with a Bosch pump in the fuel cell to a Corvette filter/regulator, finished off by a set of mandated stock 8.1L injectors. This is a manual transmission application. It will run on pump gas...not race gas.

Regardless of it's a carbureted 355 or this LS,
we keep them legal with a Dyno so this will go across the Dyno for final tuning.

Right now it still has the stock van tune in it and the stock injectors. It starts and runs. Obviously if I try to pull it now...I'll be out of injector pretty much immediately under high load. The reason I haven't installed the 8.1 injectors yet....it because from what I have seen....it won't even start with them without a tune. My MPVI is on a UPS truck en route. Looking for a baseline file that will at least get me started (literally) so I can get a head start on it and spend less time on the Dyno fiddling and focus on fueling/timing/HP. The cam is similar to a Truck Norris. As I am sure this isn't a rare combo...anyone have a file to get me started? TIA.

Here is your injector data.

226/238 .600" cam in an engine you want limited to 375HP?

Thanks for the file.

It's a little different program than what most here are going to be used to....but yes.

The goal is to hit that number as inexpensively as possible with the least number of parts. The "restrictor plate" is the tune.

The prototype is a 205,000 mile boneyard piece that got only what it needs to make that number and live. Keep in mind its second life involves trips to 7,600 RPM about 8 times per minute for about 2 hours per race weekend at that HP.

It's to convince very stubborn people that it's a better option than $7,000 carbureted 355's using 75 year old technology burning $9/gallon race gas...and blowing up once a season...But it needs to sound the part, make the power, and have the endurance. The last thing I can afford is to have it be weak in any of those categories. It definitely SOUNDS like it should, which shouldn't matter....but it does.

The reason we have the 375 rule is because there's no unified engine rules nationally...and at the end of the day we care about everyone having the same HP, no matter how they make it. We used to make it with built to the hilt 4-cylinders, then with built V6's, then with sealed crate V8's....with every step getting closer to being STOCK cars. The fans don't know how you make the noise...but your WALLET sure does!

I would be worried that unless you've got terribly lossy drivetrains eating up more than 100HP, you're going to be beyond that HP goal by quite a bit, and with a cable throttle body the only power limiting you will have is spark timing, and very low timing in the low teens or even single digits like would be needed to chop it down that much puts a ton of heat in the exhaust valves & manifolds/headers. I may be way off base but I don't think you need nearly that much camshaft to hit those targets.

Sounds like the first person to have a legitimate use case for a factory ls9 cam in an NA motor. Cheap, not much torque, and likes to rev. Paired with a factory truck intake that does NOT compliment the cam, and it might just keep the torque and HP within limits, but still spin the required rpm.

Cammed 6.0 make 325-35x all day on my mustang dyno. Stage 2 and 3 ls1 cams, various intakes, 11:1 compression.

So just got the MPVI and pulled the stock tune out of the P59. Being new to this, how does the "hive mind" work. I would love to have the stock tune from a stick shift 8.1 truck as I think it may be the easiest (laziest) starting point. Where can I get access to that tune?

https://www.hptuners.com/my-account/tunerepository/ - don't take this as an endorsement of the 'use an 8.1 big block tune file' thing, that's just not a good idea.

Yeah a Silverado 2500 would be better. That's LQ4.

Well....there is an 06 8.1L manual trans in the repository....and no stickshift 6.0L except for 2000. Understand that I was just looking to see how they have the manual trans setup in the file, and look at the injectors....not actually use that tune. I didn't word my reply well. I'm not even sure it's the same ECU. My next big question is why I don't see even half of the parameters in the VCM editor that I see in videos? I have all the tabs, and I have SOME of the parameters. Is it just something model specific? Even if I expand things there just aren't near the parameters that it would make sense to see.

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Rather easy to turn an auto trans PCM into a manual with Gen 3s, just disable all the trans-related DTCs and disable Abuse Mode. It's on Gen 4's where you can't convert them just by making edits, those have to have a dedicated manual ECM calibration.

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Originally Posted by SiriusC1024

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This is going to go swell, isn't it?

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Originally Posted by blindsquirrel

This is going to go swell, isn't it?

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I know. Wrong engine configuration for stated goals, brand new to tuning, and wrong approach. Fortunately, there are pro's on here he can contact who would be well worth it.

Thanks for everything but the condescension.

I'm sure it sounds that way to you at this point, and I know why you feel that way. But I've done and trained advanced drivability diag for 20 years, it's just in my world we aren't allowed to change the tune. I'm new to HP Tuners....I'm not new to VE calculations, speed density, fuel trims, and enrichment strategies. BUT I'M NOT GOING TO BE THE GUY TUNING IT ON THE DYNO ANYWAY....because I don't even want to. I only NEED to be able to get it on the trailer....and as a matter of fact it will already do that because it runs. Pardon me for trying to grow and stretch my legs into an adjacent field. I'm not a DIY, I'm not broke, and I don't NEED to do this at all. The reason I was ASKED to take on this project is because of my background. I literally could have skipped this whole thing on my end. Pardon me.

As to the stated goals, frankly, you don't understand them....and won't. The goal is to see what it does and go from there. Like I said. I knew when I started this that a 5.3 or maybe even a 4.8 could make that number....but what you haven't considered is as a series we have to know what is possible when someone wants to break the rules. It's more complex on that end than you may think. As far as myself personally, as someone who ran a mobile (stock) programming business for years, I thought it might be fun to actually write some ECU's with something other than stock bins. There's nothing about loading a file that excites me at this point. MAYBE I might do some things with my other personal vehicles with HP tuners....and that's a huge maybe.

I have dealt with both professional arrogance and amateur arrogance for decades. I know what both are. I've dealt with folks that think you just plug in a scanner and it fixes the car and the guy that thinks they're the best drivability tech in the world, and could actually be that good, but usually the good ones are humble.. I have zero desire to become the next great tuner. I'm doing my part to trying to keep circle track racing alive and well.

This is why I don't use forums. Sometimes you ask questions for time savings, not because you're dumb and can't figure things out. But there's always going to be someone who needs to flex on you if you do it. That's why automotive technician forums are cancer too. Learning INVOLVES MISTAKES. I'm beginning to think that coming here was one of them. If you want to help...thanks. If you can't do it without being a prick, don't.

I think what you don't understand yet (but will, when it gets to dyno-time) is that a 6.0 with a cam that big and a typical dirt track drivetrain is going to make way more than your 375/375-wheel target, and without an electronic throttle and the ability to have the tune file limit it with airflow, the only tool left in the box to limit power is spark timing and that only goes so far before things begin to melt, in an application like a race car. For a street car where the duration of power limiting is brief, it's mostly fine. But to expect it to run for sustained periods with the hammer down and timing low enough to yank out 50 or 60 HP? That's fantasy.

I may be totally wrong about my guesstimates about what a 6.0/monstercam combo will do and my guesstimates about how much loss will happen through your drivetrain but I was just trying to warn you ahead of time that there were better ways to accomplish the goal on the first try, or at least get closer. For example, where the hell do you live that 6.0L's and 8.1 injectors are cheap and readily available? You could just as well do your 375/375 goal with a 5.3L and more common injectors. Why the fixation on 8.1 injectors, mostly by the new guys who don't know what's up yet? Why do they seem to attract so many newbies? They're only 29.x lb-hr, but they're damn expensive new and not all that easy to find used, because not all that many of the 8.1 trucks were built compared to the 4.8/5.3/6.0s of that same era.

If you want help, don't be a dick when people offer you an honest assessment.

"Hi, I'm new to all this. I want to make some mistakes, do you think this will be a good place to start making some mistakes? Please don't tell me there are better ways to do it, I am VERY SMART in OTHER AREAS of TECHNICAL EXPERTISE so picking this up should be no problem for me. BTW can anyone point out where the on/off switch is for this thing? Thanks in advance. p.s. Only positive affirmation will be tolerated."

It can make more. As a matter of fact as the technical director for the series it can make whatever I say it can make. I didn't come here asking for design services. I never said help me design a 375 HP package. If that's what I was looking for I would have provided a lot more detail.

This engine, the harness, the fuel cell mods and HP Tuners is less than what our competitors are paying PER SEASON in engine costs. By any comparison. Even an LQ4 is "cheap and available".
I could skip the fuel injected route all together and tell them to put a carb and manifold and a stand alone ignition like they have always done and make WAY more. It isn't the point. I came here for HP Tuners help, not to be called a dumbass 2 days after HPT hitting my doorstep. I don't care if it works for you....I care if it works for us....and it's a program, not one vehicle. Some of it isn't going to make sense to anyone but us. The reason for the 8.1 stock injectors would be one. Imagine you are at a track, and lose an injector. The parts store by the track may have an 8.1 injector....that was literally one of the considerations. I paid $400 for a bell housing to replace a real nice (and expensive) reverse mount starter setup....just so I could run a stock starter. Why? Because you can't pick up a Quartermaster reverse mount starter at a parts store. It would have been much easier for me to keep that setup...and most of our competitors probably would. I didn't.....to make a point.

As some who spent 15 years teaching drivability to thousands of professional technicians in 46 states for 2 different well known parts companies, I may not be a pro tuner.....but I'd like to think that I at least know enough to dabble being that I have fixed a whole lot of cars with tune problems....they were just stock tunes being lied to in every imaginable way. Regardless, I know enough to not be talked to like a high school kid that think he's going to build a 1,000 HP NA stock displacement Miata.

I was able to find a lot of what I wanted to know out of the 8.1 manual tune. I didn't copy it. For instance I answered my own question about the manual trans before Sirius posted, but it was still appreciated, as was how to change the view.

I used at least 7 different manufacturers stock programming software. All of them have their quirks and user friendliness is never a consideration. I could have figured out HPT the same way as far as the view....but it was just easier to ask someone, provided that person doesn't make snide comments because I simply didn't know off the rip.

I could have had a real short career as a trainer if I walked in and told the first guy who asked me how a Lambda sensor worked in front of a class that he didn't deserve to be there if he didn't know. Or if I had assumed that because he asked, that he didn't know how to read one on a scan tool. Not everyone cares about the inner workings of nerxt cells.

My guess for the 8.1 is because it is Multitec connector? Otherwise I would of went for the flexfuel 5.3 injectors of the same era but I think that was EV6? Plus I feel like a 226 cam is pretty mild lol.

Regardless, I'd say throw in your injectors that you are going to use and copy over the injector data, then post a log with the related tune and start from there.

People sure can be sensitive to what random people on the internet think about them.

That and it is a stock OEM part which while not foolproof, makes it easier to tech and also reduces the chance that old guys turn their nose up at it. They don't know what an (x) lb/hr injector is. I just have to tell them it's from a stock 8.1L. To cheat it they'll have to find a bigger Multec injector. Not saying it can't be done....but it reduces the chance someone tries. Not everyone knows about marine injectors.

The fuel system is a Corvette fuel filter system that doesn't require permanent modification of the truck or fuel cell if they sell the truck and someone wants to run a carb engine again.

Monitoring competitors' fuel pressure is already going to be hard enough with a Corvette filter. I thought about seeing if the stock injectors can get there with just more pressure, but it gives competitors something to tinker with and then complain that it doesn't run right because they think "more pressure equals more HP".

I have to speak a language they understand, and one less modification to a harness they are already going to say "look at all those wires" at. Sales is part of the deal. The only reason I built a truck is because none of them will consider it unless I put one in front of them....and it makes enough power for them to be afraid of it.

That's the other thing I did with the 8.1 file was swap the injector data into the 6.0 tune. I'll get them installed and see what it does. I kept the MAF harness when I weeded the harness. I also used two 36 pin lever lock connectors from a Trailblazer to allow easy engine changes. Actually the LS should be easier and faster to pull than the Gen 1 small block.

The cam was chosen because it pretty much exactly matched what COMP recommended when I told them what I was doing. At the end of the day, I don't have much control over how someone builds their engine. I don't know if it's a junkyard engine or if it's a built bottom end with bigger valves I DO have to know what exactly is in the tune. One of the best giveaways something smells funny for me as the tech guy is if it doesn't run right. If I put a small cam in it... someone's going to put THIS cam in it. What they don't have access to is the tune.
We will have several PCMs so if I think something is up, I probably won't even check the CVN....we'll just swap the box. I just take the box and compare the files if they don't match.... you're DQ'd.

After this one goes across the Dyno, we'll build a 5.3 the same way, and put it across the Dyno. We'll probably have build a couple fresh engines as well. Just have to see how it goes.

Well the 8.1 injectors are in and it starts and runs. Not bad, almost all I need to do. It will idle sometimes and sometimes it idles at 2k. I can make it idle with my "finger iac" and can even stall it, but none of my scan tools nor the VCM scanner will drive down the idle. I have taken the TB off and watched the IAC go through the park sequence and the tap test with a screwdriver does seem to change....something. I for sure don't have the ve refined enough to do any final tweaking to get the counts within the sweet spot. It would idle and then once I came off idle once warmed up it hangs. TPS is at .6 and this is a completely unmolested stock TB. I played with some of the throttle cracker setting but no dice. Counts don't seem to be consistent at all.Attachment 146621Attachment 146622

You turned off adaptive idle?

I tried a couple things to see if it would help in the current tune I set the min and max adaptive idle ect to 283. Made no difference. Trying to see if that RPM is being commanded by a strategy or whether I am literally having an IAC issue. It seems too erratic to be the tune but I'm not positive. Seemed to me it was good cold and then when I got to what would be around a normal closed loop temp of about 160deg then it started to hang the idle. Since it will never have VSS or anything MPH and is manual, I wonder if maybe I missed something on the trans side? When it was idling at the desired RPM the iac was working pretty hard anywhere from single digit to 50 but I also saw counts over 100 at different times as well. No surging...just high...and when it is at 850 it will sit there and idle for 10 minutes... until you transition out of idle TPS and then it never returns to desired idle. TPS makes it back to idle, but the RPM doesn't. Did I maybe miss something in throttle cracker? I'm trying to run through all the different airflow adders in my head. As a tech I usually deal with one at a time...not all at once.

This is a boneyard engine with no history and high miles, a custom built harness for the application with extra connectors added, and very little run time because it makes your ears bleed (especially above idle in a garage).....so the possibility for "wild cards" is decent. Thanks to header paint burning off in my face I found that the original #7 injector was dead. Once I checked the harness and put the bigger injectors in, it resolved. I'm sure the lack of contribution didn't help things.

I also am not set up for wide bands and probably won't be. I do have bungs in the collectors and the van O2's in them and supported in the harness. I'm not sure whether I should plug them in or not or whether I'll just create false leans due to the cam and exhaust. Right now it actually runs better than I thought it would. Starts decent when the IAC is under control. No load of course but snap throttle is pretty crisp and other than the idle it runs good enough to start doing some street tuning just to see where I can get before it hits the dyno. I haven't even touched the VE table at this point. Today is the first day that I tried to mess with it. If I can get a predictable idle anywhere under 1,000 RPM I'll take it.

You're wasting time with idle until VE is correct. For that you need to use the narrowband fuel trims.

I don't disagree with that. I was happy that it would start and run after the injector swap especially after not touching the ve table. This is where I have a "me" problem as far as whether I just want to load it on the trailer and hand it off versus how much I want to play.

Honestly at this point I will admit to being a little bit wishy-washy as far as how far I personally will go, but knowing me and my creeping death of curiosity mixed with my background will probably lead to me spending more time on it than I should to figure it out. I was kind hoping that since I did have a kinda somewhat idle....that if I could just keep it, I would be good with loading it on a trailer.....but if I hook up the O2's and actually start doing idle tuning....I know where this goes.... 😂

Yeah but if you want to make adjustments between runs you need to know how to do it. Might as well learn.

I was afraid someone was going to say that...lol. I've learned from doing in cylinder pressure transducer graphs on street engines and experimenting with it on race engines, that race cams can absolutely make something that works stellar on a production vehicle be absolutely worthless in a different application. What are the limits of the narrow bands in this type of application?
Obviously wide band is better for staying on stoich especially at high loads/rpms. And I can totally see how you can get false leans from narrows....but how far can I trust them? I wouldn't trust them for a final answer for sure especially when the application is essentially 2 dyno pulls per lap.

On a side note: throttle hangs are absolutely TERRIFYING to a circle track driver. On the other side, some drivers will crack the throttle on entry to remove compression braking at some tracks so the transitions are going to need to be silky in the end product. I actually have to think about nightmare fuel like an IAC failing full open from a safety standpoint. May be the only application that gets a minimum air test and a MAXIMUM air test. That's also why not only drive by cable, but drive by solid cable. Standard is that the driver must have a toe loop on the accelerator and be able to (or at least attempt) to pull the throttle shut. I also have to think about a TPS failing to get back to idle voltage for the same reason....stuff that normally isn't an issue because normal people don't hurl themselves at walls at 120 mph and hope they can turn at the last possible moment...lol

No big deal tuning the entire VE table with widebands on this application. Either way, getting correct VE is your next step.