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Old 01-18-2020, 11:54 AM   #29
Eldi Z
 
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Quote:
Originally Posted by KingLT1 View Post
The LT1 indeed makes more power then a LT4 at the same PSI of boost. As you mentioned, The LT1 has a lot more compression which contributes to the increase. Honestly the LT4 supercharger works better on the LT1 because it doesn't need spun as hard to make power which equals lower blower temps. LT1's tend to dyno around 600whp on 9 psi and not 550whp like the LT4 on 93. The down side is the LT1 runs into a octane wall on pump gas around 10psi. So you need to supplement with Ethanol blend or Meth. LT4 can potentially make a lot more power on 93 octane with it's lower compression.

It's a good swap if you don't plan to go very far. I personally would run a larger 7psi pulley and run a blend of ethanol(E60) with LT4 fuel system. It will soften the hit since the little 1.7 makes a boat load of torque down low and still make the same if not a little more power up top as the 9 psi pulley on 93.
Good points.
For instance, my personal goal is no more than 570-580 RWHP tops. I do not plan on drag racing - just to increase my daily "fun factor" a little.

I guess that for such power goal the sweet spot for a clean pump 93 (no E and no Meth additions), would be 8 PSI of boost on moderate and safe timing advance?
From most of the information posted, so far the weakest link is the tight ring gap on the LT1 pistons, which calls for extra care when boosting.
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Old 01-19-2020, 01:53 PM   #30
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Quote:
Originally Posted by Tim M View Post
Heater: Great feedback on you experiences. Not sure about the comment, "produce a little more power due to heat." Possibly I took that out of context, but more heat will produce less power. Possibly the LT1's cam may produce more boost than the LT4...but I'd chalk that up to not an ideal blower cam.

I'm not an expert, but I'd think the cam is not such a benefit to the LT1 with a blower. Yes the intake lift/duration is greater than the LT4, but you have boost benefiting the inflow. Notice the exhaust is less for lift and duration on the LT1 compared to the LT4 - an area that the blower does not help. In other words, the LT4 has a blower cam and the LT1 has a NA cam. How does this impact long term longevity of the engine/cats...

I'd suggest (as others have) the 1.5 point of compression increase on the LT1 is the source of any 'extra' power...I'm not sure a LT4 blown LT1 makes anything more than the LT4. Doing so means the power is made differently with a weaker piston design. Why does Chevy go with a lower CR...reliability, no doubt-just like oldman states on minimal cam actuation/valve springs.

I've asked about better valve springs when going from NA to blower and was told, not necessary. I used to change valve springs out seasonally on my 7200 rpm LT4 (Gen II) motor as they were consumable. I'll probably address in the future as boost on the backside of the valve reduces the resulting spring pressure - I do like to hear those 6500 rpm shifts!

I'm interested in the discussion only because I will be putting the stock LT4 blower on my LT1...may not be the best idea for my application, but can't deny the need for 650 HP!

I'm at 1100 feet elevation so will report back what boost it runs with an OEM LT4 blower/pulled as well as OEM intake setup.

Thanks!

Not sure why i said "produce a little more power due to heat." but clearly that is false, i think i meant to put a comma and probably meant to write compression after! nice catch!
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Current Mods: LT4 blower, Kooks 2" headers, CAI, LT4 High Pressure Pump, LT4 Injectors


Mods to be installed in coming weeks: Alky Control Meth Kit, BTR Stage 2 Cam and Spring Kit + DoD Delete, LT4 Low Pressure Pump, Skid Mark Garage E85 Sensor, Skid Mark Garage Aux Pump
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Old 01-19-2020, 01:57 PM   #31
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Quote:
Originally Posted by Eldi Z View Post
OK. Now I get it.
The stock pulley of the LT4 should be avoided, since it is too small (spins too fast) when working on the LT1.
So when you get the kit (Incl. Blower) from ADM (or WeaponX too?) they supply the blower with the larger Pulley already installed on it?

You are lucky to have a knowledgeable tuner on LT Gen5 ECMs and engines close to you
I think that I would have to rely on remote tuning when the time for my job comes.
I do have a couple of dynos close by, but I don't trust local tuners on the LT Gen5 platforms (yet). There are 2 tuners around who are very good on LS setups, but I am looking for experience and perfection on the LT/Direct Injection setups.
Unfortunately this place is "ruled" by EURO Import material (VW, BMW, Mercedes, Porsche, Etc.) and less GM/Ford/Chrysler. But it has improved slightly in the past 2 years with an inflow of C7s, SS, ZLs and CTS-V/ATS-V machines.
WX installed the griptec hub and supplied the griptec pulley which is super easy to put on as it is like small bolts to install. So if you ever change it you just need to buy a pulley and belt and can install it pretty much anywhere.
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Mods to be installed in coming weeks: Alky Control Meth Kit, BTR Stage 2 Cam and Spring Kit + DoD Delete, LT4 Low Pressure Pump, Skid Mark Garage E85 Sensor, Skid Mark Garage Aux Pump
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Old 01-19-2020, 02:42 PM   #32
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Intake duration directly increases power period 189 duration is just TOO small. exhaust duration indirectly increases power by reducing pumping losses.

Look at the smallest cam Cam Motion makes for the PD: 220 /236
"to be used in completely stock vehicles"
That is an intake change of 31 degrees and an exhaust change of 13.

Somebody has Camdoctor and can give a figure on how much a LT1 cam add in HP or not. IMO the LT1 cam produces more HP i.e. the ingestion of more intake charge. Would be interesting to find out...

Since there is so little here on either cam, I consider this angles dancing on pins. I am NOT saying the LT1 is an optimal supercharger cam, obviously it is a NA cam.
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2016 to 2017 Stage 1, FBO, ported MSD, 103 TB, E85

2018 Stage 2, P1C, 4.0 pulley, Pray ported heads, Pray stage 1 blower cam, TxSpeed valvetrain, Katech ported 87mm TB, ported MSD, 1 and 7/8 headers

2019 stage 3: Forged short block 11.5 CR, huge duration sub .600 lift Cam Motion cam, Pray Ported Heads, 3.85 pulley D1X, stage II intercooler, 2 BOVs, DSX secondary low side, DSX E85 sensor, Lingenfelter big bore 2.0, CA-offroad pipe, 60609 Borla, Lingenfelter injectors, ZL1 driveshaft and half shafts, Katech ported TB,MSD intake, BTR valvetrain.

Last edited by oldman; 01-19-2020 at 03:19 PM.
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Old 01-19-2020, 02:53 PM   #33
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Quote:
Originally Posted by Tim M View Post
I've asked about better valve springs when going from NA to blower and was told, not necessary. I used to change valve springs out seasonally on my 7200 rpm LT4 (Gen II) motor as they were consumable. I'll probably address in the future as boost on the backside of the valve reduces the resulting spring pressure - I do like to hear those 6500 rpm shifts!
what you wrote is gospel truth. I too consider valve springs consumable. In general over the past 32 years race 4 valve engines. So boost over the valve head did NOT require stronger springs (heads really small). I'm of the opinion now with these huge valves that boost does require stronger springs or you subject the intake valve to bounce as the related lifter overshoots the lobe and deceleration ramp and impacts on the cam. Think of it as a motocross overshooting the landing. This fails either the lifter or the valve (probably the hollow intake), in my case the lifter. I think this problem is further complicated by dual valve spring harmonics (should have gone conical), fast lobe lifts (add HP and brings customers in), and extended RPM, and most importantly large valve lifts (customers like that too). Try 7000 RPM sifts... OMG sounds great. Especially with a near stock exhaust that you can actually hear the metallic engine sounds.... not just loud exhaust. I posted an idle rev video on the NA section of large cam and stock exhaust.

BTW always luved the LT4 as the final evolution of the SBC.


Quote:
Originally Posted by Tim M View Post

I'm interested in the discussion only because I will be putting the stock LT4 blower on my LT1...may not be the best idea for my application, but can't deny the need for 650 HP!
Price seems good, performance better than stock LT4, looks bad action. It was my first choice.
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2016 to 2017 Stage 1, FBO, ported MSD, 103 TB, E85

2018 Stage 2, P1C, 4.0 pulley, Pray ported heads, Pray stage 1 blower cam, TxSpeed valvetrain, Katech ported 87mm TB, ported MSD, 1 and 7/8 headers

2019 stage 3: Forged short block 11.5 CR, huge duration sub .600 lift Cam Motion cam, Pray Ported Heads, 3.85 pulley D1X, stage II intercooler, 2 BOVs, DSX secondary low side, DSX E85 sensor, Lingenfelter big bore 2.0, CA-offroad pipe, 60609 Borla, Lingenfelter injectors, ZL1 driveshaft and half shafts, Katech ported TB,MSD intake, BTR valvetrain.
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Old 01-19-2020, 03:04 PM   #34
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The octane limit of about 10 PSI on 93 is a good rule of thumb, there is some flex of course because we all know boost is related to restriction. So 10 PSI of boost on stock engine is not filling the chamber up as much as 10 PSI of boost on a heads, cam, header engine. Same goes for where the boost happens, 10 PSI on a twin turbo big cam engine reaching this boost at say 5500 RPM has far less detonation potential than 10 PSi on stock lt1 with a 1.7 PD pullied at 2800 RPM, there is going to be more fuel, air, and much slower piston speed, all of which contribute to detonation (charge heating too adds to detonation). Gut feeling and I don't want to test the limits here, the 1.7 PD on stock engine is about 1 psi lower than this rule of thumb and a twin turbo, large cam built engine is 2 PSI above (assuming relatively lazy turbos). That 3 PSI swing, added to better flowing build engine does equal a WHOLE lot of HP when all is said and done. .i.e 11.5 CR is octane limited, but within this limit different builds probably vary by say 70 HP or so (granted it is expensive HP).

On my 11.5 CR build, the most knock retard I've seen to date is like 1 degree and Texas can get heck of hot.. all on 93. I'm on E85 tune now.
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2016 to 2017 Stage 1, FBO, ported MSD, 103 TB, E85

2018 Stage 2, P1C, 4.0 pulley, Pray ported heads, Pray stage 1 blower cam, TxSpeed valvetrain, Katech ported 87mm TB, ported MSD, 1 and 7/8 headers

2019 stage 3: Forged short block 11.5 CR, huge duration sub .600 lift Cam Motion cam, Pray Ported Heads, 3.85 pulley D1X, stage II intercooler, 2 BOVs, DSX secondary low side, DSX E85 sensor, Lingenfelter big bore 2.0, CA-offroad pipe, 60609 Borla, Lingenfelter injectors, ZL1 driveshaft and half shafts, Katech ported TB,MSD intake, BTR valvetrain.
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Old 01-19-2020, 07:34 PM   #35
Eldi Z
 
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Quote:
Originally Posted by oldman View Post

On my 11.5 CR build, the most knock retard I've seen to date is like 1 degree and Texas can get heck of hot.. all on 93. I'm on E85 tune now.
So if you look back to the days of your LT1 being in its stock form (Incl. exhaust End-to-End) and you would go with the LT4's Eaton 1.7 PD blower setup, but adding all of the LT4 fueling parts (Injectors, HPFP, LPFP-InTank & Related Fuel lines) on "pure" 93 Pump, that does not contain any E at all, nor would you add meth! -
At which boost levels would you feel "safe" not damaging the motor (I.E.knowing that the top ring gaps are tight).

What would you expect the perfectly "detonation free" RWHP to be at such boost level?
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Old 01-19-2020, 08:40 PM   #36
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My engine still has cam and ported heads as well as a slightly lazy centri (d1x), I'm comfortable at 10 PSI on 93 with forged pistons.

I have not looked into pullied 1.7 on a stockLT1 engine, I think the LT4's stock boost is in the high 9 range, so we know what GM believes. I would look at a shop or somebody that has the car and see what they think. There have to be many guys now with this setup. IMO I like only builds capable of 100,000 miles. My first build was temp till I retired and even then within 5k or so miles I had a lifter failure. No bigs as I was going to change the cam and lifters on the rebuild, but scary it could have taken out the engine. My pistons look fine... mint in fact, don't know if I was lucky. Nut shell even at stock LT4 boost, you are starting with an engine with higher CR and cast pistons, at some point getting rid of pumping losses makes more sense vs boost.

I do think the front cats are very restrictive and will be putting in CA front cat deletes with Borla 60608 twin resonator mid-pipe (hope this keeps the sound near stock. If this does not work, I will put two high flow cats into the system, bringing the total to 4 cats, two resonators, two crush pipes, stock exhaust pipe. At some point, it has to be quite? I have tried 20 different combinations to find something I'll be happy with over the life of the car (1 to 20 years).


IMO this would be my first mod after blower; my only issue with any upgrade to the exhaust is my M6 car with my mods sounds terrible with no cats and just plain heck of loud with LT and cats. I'm looking for something fast but near-stock at 45 MPH or completely stock.
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2016 to 2017 Stage 1, FBO, ported MSD, 103 TB, E85

2018 Stage 2, P1C, 4.0 pulley, Pray ported heads, Pray stage 1 blower cam, TxSpeed valvetrain, Katech ported 87mm TB, ported MSD, 1 and 7/8 headers

2019 stage 3: Forged short block 11.5 CR, huge duration sub .600 lift Cam Motion cam, Pray Ported Heads, 3.85 pulley D1X, stage II intercooler, 2 BOVs, DSX secondary low side, DSX E85 sensor, Lingenfelter big bore 2.0, CA-offroad pipe, 60609 Borla, Lingenfelter injectors, ZL1 driveshaft and half shafts, Katech ported TB,MSD intake, BTR valvetrain.
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Old 01-20-2020, 09:00 AM   #37
Eldi Z
 
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Thanks for the insight oldman.
Yes, best thing is to ask around people running this setup for a while. Assuming GM is comfortable with ~ 10 PSI on an engine with 1 point lower C/R and with forged material, then my guess for a "safe" boost on a 1 point higher C/R with non-forged material should be ~ 7-8 (Max.) PSI - and yes, no less than 100K reasonable use (not "beating on her") miles longevity is the target.
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Old 01-20-2020, 04:00 PM   #38
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Originally Posted by Eldi Z View Post
Thanks for the insight oldman.
Yes, best thing is to ask around people running this setup for a while. Assuming GM is comfortable with ~ 10 PSI on an engine with 1 point lower C/R and with forged material, then my guess for a "safe" boost on a 1 point higher C/R with non-forged material should be ~ 7-8 (Max.) PSI - and yes, no less than 100K reasonable use (not "beating on her") miles longevity is the target.
IMO that is conservative, I like that. I'd do GM's high 9s (on 93) and work on the exhaust with either CA cat deletes move the 02 behind the second cats, or for an auto LT with cats. I know I'm "avant garde now" Also RotoFab, both mods reduce pumping losses so it is stress-free HP, which is longevity HP, ported tb and snout too. I figure the blower is probably optimized for high 9s and a 6.2 liter engine (never saw an efficiency map on it), I figure the aftermarket is doing plus 70 to plus 100 on a LT4 so dunno 12 to 14 PSI which has to be WAY off the efficiency map. We are dealing with a temp rise in either case, either before the intake valve or mechanical compression.

I hope others with the actual build will chime in. I would expect the build to be very responsive and fun.
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2016 to 2017 Stage 1, FBO, ported MSD, 103 TB, E85

2018 Stage 2, P1C, 4.0 pulley, Pray ported heads, Pray stage 1 blower cam, TxSpeed valvetrain, Katech ported 87mm TB, ported MSD, 1 and 7/8 headers

2019 stage 3: Forged short block 11.5 CR, huge duration sub .600 lift Cam Motion cam, Pray Ported Heads, 3.85 pulley D1X, stage II intercooler, 2 BOVs, DSX secondary low side, DSX E85 sensor, Lingenfelter big bore 2.0, CA-offroad pipe, 60609 Borla, Lingenfelter injectors, ZL1 driveshaft and half shafts, Katech ported TB,MSD intake, BTR valvetrain.
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Old 01-21-2020, 12:15 PM   #39
Eldi Z
 
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Quote:
Originally Posted by oldman View Post
IMO that is conservative, I like that. I'd do GM's high 9s (on 93) and work on the exhaust with either CA cat deletes move the 02 behind the second cats, or for an auto LT with cats. I know I'm "avant garde now" Also RotoFab, both mods reduce pumping losses so it is stress-free HP, which is longevity HP, ported tb and snout too. I figure the blower is probably optimized for high 9s and a 6.2 liter engine (never saw an efficiency map on it), I figure the aftermarket is doing plus 70 to plus 100 on a LT4 so dunno 12 to 14 PSI which has to be WAY off the efficiency map. We are dealing with a temp rise in either case, either before the intake valve or mechanical compression.

I hope others with the actual build will chime in. I would expect the build to be very responsive and fun.
I think that the maximum boost levels that most tuners recommend for this relatively small 1.7 blower is ~ 10-11 PSI - No more.
Again, lets have people with this set-up chime in with more information.

Thing is, that I would not like to impair the emissions requirements, by deleting the CATs and potentially fail smog tests.

Regarding intake: The stock inbox can be modified (I.E. Drill openings at the bottom): i would like to remain with a panel filter too - There has been no significant (if any) gains proven by using a conic/round shaped filter (I.E. K&N, Rotofab, Etc.).
Ported TB is already installed BtW (Soler)
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