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So for the street, would the vsr gen 2.5 billet 7875 1.25 ar t4 be a decent flowing turbo for this 6.0L and this summit cam?
Okay so with this question you have to consider future power goals.
The VSR 7875 turbo will be an absolute hoot on the street, the average power throughout the range will be excellent, outta make 700-800whp before the small 75mm turbine becomes a restriction.
There are lots of guys on here running well into the 9's with a 7875 turbo so unless you foresee 1000whp and 8 second 1/4 mile passes in your future, the 7875 will suite you great, be way more cost effective and far more easier to package as well.
If you intend to go beyond the 7875's capabilities then switching to a T6 setup is inevitable which may require changing your entire setup.
Put an electric cutout a little down stream of the turbo too and you'll be very happy.
I appreciate, and yeah as I read more into and watch Richard Holdeners videos on 7875s, with the t4 frame its gonna spool nicely but will choke pretty quick in the upper rpm. I'm thinking for now this will do and be amazing for a street car. even at 800hp, that's more than new zo6 or hellcats with a lot less weight to boot 😁 not to mention a lot less electronic nannies.
I think this 6.0L junk yard build will be my test mule for learning what i like and then see what I can improve on. I'm gonna find an ls3 or even an LY6 later on and that will be my ultimate build with forged internals and other goodies.
I appreciate, and yeah as I read more into and watch Richard Holdeners videos on 7875s, with the t4 frame its gonna spool nicely but will choke pretty quick in the upper rpm. I'm thinking for now this will do and be amazing for a street car. even at 800hp, that's more than new zo6 or hellcats with a lot less weight to boot 😁 not to mention a lot less electronic nannies.
You can't (and shouldn't) rely 100% on anyone's videos.
I disagree with the bolded part above, only because I am just an average Joe, and have not experienced it in an actual, in car, drag race, WOT, datalogged, scenario. No idea of my backpressure, nor do I really care, to be honest, because the car runs well. The ONLY time it ever has wavered, was when the single wastegate wasn't controlling boost. On that day, my car hit a solid wall, in power and boost, at running 147 mph, and 22.5#...
I like watching the Richard Holdener videos just as much as the next guy, but they're also DYNO videos, not real world, in car, down the track findings.
I attached a datalog screenshot from a month ago (1st pass of 2021)...
This was a 9.90@140
6.0 LQ4 powered 2000 Trans Am (with a 4060# race weight)
VSR NextGen (aka Gen2) 78/75 billet turbo w/.96A/R and 3" turbine outlet
Open 3" downpipe (cutout just beyond starter)
* BOOST, the purple line in 2nd group of graphs, is rock steady the whole pass...
Well, at least up until I let off the gas at 145MPH and 6600 RPM in top section of graph.
As for believability of these "famous" guys doing videos, just look at the infamous "Sloppy" Colorado Gen 1 to Gen 2 78/75 turbo swap claim of GAINING 100RWHP...
The only 100 in the whole thing is that it's a 100% Bullshit claim.
First, it was 92hp, (ok, no biggie there), if I remember right, BUT...
Second, Third and Fourth...it was on a different DAY, on a different DYNO, and the truck was RE-TUNED for the new turbo...lol.
So...apples to watermelon comparison.
I have no doubt it picked up some hp...Heck mine went from 9.92@138 to 9.76@142 with NOTHING done, except the actual turbo swap, from a Gen1 cast 78/75, to NextGen billet 78/75, and ZERO re-tuning. Honest HP gain at same boost, same track, near identical weather stats, but I'd bet that it isn't 100 WHEEL HP.
Just that video "test" (& claim) sticks out...mainly because it's mis-leading.
Then, fast forward to Engine Masters Videos, and the infamous, tuned/jetted CARB to out of the box, FITECH or SNIPER EFI swap (can't recall which), where they claimed the carb made more power everywhere, vs. the out of the box EFI unit...lol. Well, of course it did. The EFI setups need to be tuned, or at least have some LEARNING TIME...
That'd be like me taking my street/strip tuned and tweaked factory ECU out of the mix, throw on a Holley TerminatorX, tow it to the track, fire it up (for 1st time), make a pass and be disappointed, then claim the Holley was junk...LOL. See where I'm coming from?
I love data, and log every dragstrip pass, as well as write it down in my log book. I still suck at bracket racing, but I got, and get, good data, LOL.
Sorry to rant...
Fact of the matter is, YES, you surely can make more power with a bigger turbo on a 6.0...
But, on an HONEST Street/Strip car like yours or mine, it's hard to beat the well proven 78/75 for ALL AROUND useable power.
I actually have a 1.25 A/R turbine housing for my car, but don't intend to swap it until near the end of the 2021 racing season. VSRacing says it should gain me enough power to run 5-6 MPH faster...I really doubt that, and I won't be convinced it's really even needed (or desired) until I prove myself wrong...
You can't rely 100% on anyone's videos.
I disagree with the bolded part above, only because I am just an average Joe, and have not experienced it in an actual, in car, drag race, WOT, datalogged, scenario. No idea of my backpressure, nor do I really care, to be honest, because the car runs well.
I like watching the Richard Holdener videos just as much as the next guy, but they're also DYNO videos, not real world, in car, down the track findings.
I attached a datalog screenshot from a month ago (1st pass of 2021)...
This was a 9.90@140
6.0 LQ4 powered 2000 Trans Am (with a 4060# race weight)
VSR NextGen (aka Gen2) 78/75 billet turbo w/.96A/R and 3" turbine outlet
Open 3" downpipe (cutout just beyond starter)
* BOOST, the purple line in 2nd group of graphs, is rock steady the whole pass...
Well, at least up until I let off the gas at 145MPH and 6600 RPM in top section of graph.
As for believability of these "famous" guys doing videos, just look at the infamous "Sloppy" Colorado Gen 1 to Gen 2 78/75 turbo comparison claims of GAINING 100RWHP...
The only 100 in the whole thing is that it's a 100% Bullshit claim.
First, it was 92hp, if I remember right, BUT...
Second, Third and Fourth...it was on a different DAY, on a different DYNO, and the truck was re-tuned for the new turbo...lol.
So...apples to watermelon comparison.
I have no doubt it picked up a decent amount...Heck mine went from 9.92@138 to 9.76@142 with NOTHING done, except a Gen 1 cast 78/75, to Next Gen billet 78/75 and ZERO re-tuning. Just that video "test" sticks out....
Then, fast forward to Engine Masters Videos, and the infamous, tuned/jetted CARB to out of the box, FITECH or SNIPER EFI swap (can't recall which), where David Freiburger claimed the carb made more power everywhere, vs. the out of the box EFI unit...lol. Well, of course it did. The EFI setups need to be tuned, or at least have some LEARNING TIME...That's be like me taking my tuned and tweaked factory ECU out, throw on a Holley, and tow it to the track and expect it to outrun what I have/had...LOL.
Sorry to rant...
Fact of the matter is, YES, you surely can make more power with a bigger turbo on a 6.0...
But, on an HONEST Street/Strip car like yours or mine, it's hard to beat the well proven 78/75 for ALL AROUND useable power.
I actually have a 1.25 A/R turbine housing for my car, but don't intend to swap it until near the end of the 2021 racing season. I won't be convinced it's really even needed (or desired) until I prove myself wrong...
Good Luck!
You were actually who I was referring to and was hoping you'd chime in to lend your firsthand experience. ; )
Holdner has a video somewhere addressing the very points rel3rd brings up. The engine dyno is more of a scientific learning tool for engine tuning where you can make these individual changes and gather tons of really precise and repeatable data. The key there being repeatable. You can make the dyno run the engine as close to exactly the same as the last time each time. Same torque load, same air temp, etc...controlled environment. He fully acknowledges it does not tell you how a given car will take to it.
The dyno videos are great for seeing how hammering on a header tube to make it fit will change it's performance, length of hot side and cold side piping effects on turbo lag...stuff like that is neat. Which cam is best, which intake is best, which turbo combos you should pick and stuff like that not so much.
dang, looks like I'm gonna be building and installing this lq4 in the bird sooner than I thought.
Had a head gasket leak that hydroloc #6 piston and the rod said bye bye. had some vavle love taps on the piston but didnt fins out it was busted until i started wiping the cyclinders out and i barly pushed the piston down the bore lol tall tell signs of coolant leaking my poor head lol
Currently on the LQ4:
Stock LQ4 block honed and cleaned up
stock LQ4 crank,
stock gen 4 rods,
Stock ls2 flat top pistons
new journal bearings
new ls1 oil pan
new aluminim oil barbell
new lq4 head studs (ls1 used the weird ones)
Swapping over from old LS1:
summit stage 2 turbo cam
stock 241 ls1 heads,
stock ls6 intake,
80lbs deka injectors
tsp vavle stems
pac valve springs
Michigan trunion upgraded rockers
LS to 4l80 flex plate
ls9 head gaskets
ls1 exhaust manifold gaskets
summit cam retainer plate
Nicks remote powers steering pump kit
alternator relocation bracket
other various little sensors and attachments
finally got some motivation and time to do something today lol
tore down the semi put together LQ4 to ball hone the cyclinders. also cleaned up the deck surface some more so I don't have any excuses for coolant leaks lol
hello 240 grit Flexhone fresh out of the box A little lube and 20 strokes... im building an engine right? 😆 As you can see, it had a very nice mirror finish before the start not too shabby for my first dingleball honing if indo say so myself. Again, all im doing is removing the glaze so the new piston rings will seal nicely. 240 grit Flexhone did ita job well i did one bank at a time with liberal amounts of ATF on each cyclinder. After cleaning the cyclinders, these bad boys are ready for a slug. Can't say it's a perfect 45degree, but damn not bad for eyeballing it huh? Decided to go with a holly sniper to clean up my intake a little. got tired of the old ebay hunk not sealing well. opting for the high pressure standard volume melling pump, over the ls6 pump. might as well, the prices are too good to pass up right now for the holidays.
Main caps torqed and angled. such a weird proceedure. heres the old 80mm TB im getting rid of. god its big for no reason sealed power pistons rings waiting to be gapped out you go! heres the gaps im gonna go with. looking at .024 top, .026 for 2nd ring. hut still doing a little research before i file them was looking at this chart too for assistance. what's confusing is using this chart, for boost its saying .028 for the rings
I would not buy anything important from Amazon... definitely not an oil pump that could be a knock off. Should be a fun new setup... I like IWIS timing chains if you plan to upgrade. 10295 is my go to pump also.
BTR has their brand of LS9 head gaskets that are very affordable plus Point One head bolts/studs.
goal for the car is just something fun to drive and hit the track when I can. powerwise I'm aiming at being able to hold 18psi of boost and hit 800hp potentially.
Got some Christmas after goodies in the mail lol decided to clean up the ls6 intake and fit the Holley 92mm TB and the ICT 3 to 4 bolt adaptor on it. decided to use the cap bolts over the allen bolts on the outside. be warned, you have to shave about 1/8" off the short bolts if you chose to do this like I did, as the bottom bolts unmodified hit the intake slightly. nothing a little grinder can't fix but shame to have to do that to some new Shiney bolts lol
looks 10 times better than the ebay special i had on there and i lile that i have more lop on the new throttlebody for the coupler to hold onto. side by side comparison. dont even know the brand name on the silver one lol but its an 80mm or 85mm if i remmeber right. the adaptor plate from ICT is a nice touch. i know necking down from 92 to 78mm on the LS6 is a choke point, but its boosted, and like i said, this is more for looks and potential builds later. didnt realize how small the opening was on these LS6 intakes for all the hype lol adaptor installed with recessed allen bolts. pretty typical. oring seal came with the adaptor plate instead of some paper gasket the old one had lol and all snugged up and ready for action
curious if I did this right. it's been awhile since I concerned myself with compression ratios lol
with an LQ4 4.0" Bore, stock crank and rods, ls2 pistons, with ls9 gaskets and ls1 241 heads at 66.67, looking at 10.5CR. had to use the drop down for ls2 engine but same difference as a 6.0L.
yeah I've seen that, but over the years, more and more people are making power and not sacrificing low-end for boost. while this opens your tuning window, it leaves a little to be desired for street manners. the benefit besides low-end tq out of boost, is less need for boost for the same amount of power desired. Back pressure will also be less due to less need for boost to be cranked up. As long as tuning is meticulous and not greedy with timing, should be a fun time. ran my ls1 on 14psi for years at stock CR.
Well pulled a bunch of turbo stuff and cooling parts out of the way to prepare to pull the engine. was gonna try and yank out the cam, but the crank was giving me a hassle, so I'll wait until I can crank on it with the impact better.
Did a bunch of cleaning on the engine and cyclinder heads. decided to juat get new BTR ls9 gaskets, wasn't sure with all the copper spray on the old ones if I need to clean them off and if they hold up to being cleaned off.
Also decided against reusing the ls7 lifters and ordered a set from BTR as well. didn't like how the ones coming out of the old LS1 looked, and a couple lost their top retaining clip for some reason so nope! lol poor little guy lol just waiting to be plucked. so far everything has been yanked up top. havent jacked the car up yet. gotta disconnect the transmission and tq converter. got the lifting plate inplace. yes I'm gonna remove the oil sensor before I pull the engine bunch of random parts laying around lol, i swear theres a method to the madness little gt45 and the merge still attached. supringly easy to yank out once the radiator is out of the way not bad for a home cleaning job cleaned up the LQ4 pretty damn good Cleaned up all the old 241 heads pretty good. still can see the original machine marks from factory, so i didnt completely mess it up lol
yeah I've seen that, but over the years, more and more people are making power and not sacrificing low-end for boost. while this opens your tuning window, it leaves a little to be desired for street manners. the benefit besides low-end tq out of boost, is less need for boost for the same amount of power desired. Back pressure will also be less due to less need for boost to be cranked up. As long as tuning is meticulous and not greedy with timing, should be a fun time. ran my ls1 on 14psi for years at stock CR.
Understood. In my case, high stall converter and 4.1 gears takes care of street manners. OD takes care of highway. Boost comes on almost instantaneously if needed.
it seems I might need to flip those around. I assembled them with the rod dimples to the rear, but some how missed the piston tops. does it matter in the grand scheme of things? it's not too difficult, yet to yank them out and flip them around.
Finally got the damn summit c2500 crank off. Couldn't get my impact to twist this damn ARP bolt off. finally got a small prybar to wedge in one of the holes. then it took me a sec to figure out how to use my crank puller in the tiny holes but got it eventually, where I finally could yank out the Summit cam and set that aside.
Then i started cleaning up and organizing my parts that are going in the LQ4 and what will go into an LS1 rebuild eventually. Laying out all my major components and make sure I have everything. think im gonna just get a new chain and leave the ls2 chain in the ls1. just don't feel like fighting the oil pan in the car right now lol, plus it will let me have a ls2 chain for the ls1 later. gonna leave the ls6 pump on the ls1 while the melling high pressure pump will go on the LQ4.
Mostly juat happy to get the crank and cam out of the hurt LS1. Also glad to see nothing happened to the cam lobes.
Guess im almost ready to pull the engine. gotta finally lift the car and disconnect the transmission and torqconverter bolts. gotta transfer over the flexplate over too.
Gonna grab an LS2 chain and some UMI Poly motor mounts and get ride of the stock style motor mounts that I did do a poly bushing upgrade a decade ago. Kinda want to redo the oil catch can setup too. looking at mighty mouse or motorworks but dang those are expensive for what they are. they do look good though.
Out comes the Summit stage 2 turbo cam. plenty of room when theres nothing in front of the engine lol as you can see when the radiator and everything else is put of the way, the cam has plenty of room laying everything out to begin final cleaning and prep for install New clean pan with gasket and hardware. front and rear engine covers, along with the melling oil pump. new ict hardware for pretty bolts lol Got the front timing chain cover with oil drains on them. summit turbo cam and ls6 valley cover with breather newer ls1 water pump and gasket, with arp harware. kinda want to do a steam vent kit, but this one will work for now. stock 98 coils thta will be going on the ICT bracket, liked the look better. comes with regular cap bolts over these allen bolts that rusted in less than a year which made me mad. New rockers with trunion upgrades, and ls1 manifold gasket. a little closer look of the rockers Gonna try these LT1 wires to see if they clear the Cxracing manifolds better as some have mentioned. they have nice short 90* plug side and long enough to run under and around. heres to hoping. If not... Huron might be getting a call from me before February for their group purchases lol new BTR LS7 and lifter cups. cheap insurance after i didnt like the ones i yanked out of the ls1. they got milk on them and some had surface rust on them. didn't like that. another look at the ls6 valley cover. gotta clean it up a bit. had this on since 2010. See its a summit cam lol GT45 waiting to be replaced. wondering if I should hack off the wastegate and get a better one. project paralysis is real 😆 Griffin radiator. pretty basic for stand up radiator. the fans are cheap e b a y fans lol but i have some Derale fans waiting to replace these. i had room to use this as pullers, im gonna see if i can make the derales pullers too but not with the 7875 going in there.
Last edited by JoshuaGrooms83; 12-31-2023 at 01:36 PM.
05-05-2021, 02:22 PM
