Lt4 blower swap
 

I picked up a weapon x kit second hand and am looking for a set of instructions before I get started. Does anybody have a set they could help me out with? Thanks

I believe some just used the Magnuson install guide being there is no instructions for the LT4 swap. Some things are different and but a lot of it relates.

Sounds good. I’ll give that a shot

Awesome. I apprehended offer. Planning on getting started in a couple of weeks. Need to grab a couple replacement seals yet

so when you do one of these kits how do you address the vacuum bypass...
my understanding is that it is electronically controlled in the zl1 how do you adapt that to work ….

so you are always under boost...

im trying to figure out if there is a way to adapt the lt4 setup to my eforce 2300
mine is vacuum operated and sometimes feels like an on and of switch, I'm waiting for a nitrous jet to put in my vacuum line to slow down the effect and that might work but it seems to me that the electronic control is the way to go, however I see that could get complicated real fast, so just wondering about how people with the lt4 swap kits do it..

Who tuned the ECM? Is it done with HP Tuners?
Is there a way to maintain the electronically controlled bypass?
Are you running on 93? Which kind of boost levels and RWHP do you see?

Thanks Heater for this input.
Does it mean that your bypass operates as it does on a stock ZL1, despite the fact that you did not wire it to the ECM like BlueCamaro6 did? Otherwise, how can it work for you?
What about the IAT #2 that he managed to wire up as well?
I shall be following your build as it goes along...getting interested in the LT4 swap alternative.
Why are you running only 91 and not 93? You could pick up some safe RWHP by being able to advance ign. timing a bot higher.

So nowhere in your area you can get even a single station with higher than Octane 91?? That is bad news :mad0259:

Anyway, did you get the complete installation "kit" from ADM (Andy M)?
If so, can you provide information as to completeness of the components included, meaning: Was everything you needed for the conversion included?
If not, which additional parts did you have to source by yourself?

What about the blower itself? Did you get it from Andy M as well? Is it a take-off from a ZL1 / CTS-V, or a Z06?

Finally, how did you go about the installation? As far as I am aware, ADM does not provide a "manual", nor does WeaponX....

Understood. So you can recommend both WeaponX and ADM for the components of such mod?
Was the use of the adapter plates and swapping the valley cover an issue requiring a great deal of DIY, or was it a straight forward job?

BtW, why did you end up getting the possibly water-damaged replacement wiring loom from ADM and not from WeaponX (your "original" supplier)?

Actually, I am looking for a streetable application. I am not into drag racing - just thinking of a bit more "fun" power. The fact that the blower is relatively quiet and not whining is an advantage for me as well - not a drawback.

I believe that using (maybe) one size smaller pulley, LT4 Injectors & LT4 FPs (+LT4 Fuel fittings) on 93 can get me to around a "safe enough" 560-580 RWHP, which is my ball-park goal. Idea is to also avoid having to go into the motor, in order to replace Pistons / Rods.

Thanks Heater for the details!

The only reason I could think of that the LT1 with a blower produces more power than an LT4, would be the higher C/R of the LT1 (11.5 LT1 Vs. 10.0 or 10.5? LT4).
Why would there be a difference in heat (lower for the LT1 with the exact same blower mounted)?
Why did you put a larger pulley, rather than leave the stock LT4's 2.5?

Finally, who tuned the ECM? Was it performed on a dyno, or did you log on the street and had it sent to the tuner for mail tuning?

The LT1 has a much bigger cam too.
I went with Pray Procharger setup (with heads, cam tune), but would have been just fine with ADM, price seems great.

What do you mean in terms of Big?

What is the Lift/Duration on the LT1 and what is it on the LT4?

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 :w00t:
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.

LT4 Cam Specs
Part Number 12642245
Duration @ .050 in. (int./exh.) 189°/223°
Valve Lift (int./exh.) 0.492 in./0.551 in.
Lobe Separation Angle 120°

tiny in fact.


L86 Camshaft Specs
Part Number 12629512
Duration @ .050 in. (int./exh.) 200°/207°
Valve Lift (int./exh.) 0.551 in./0.524 in.
Lobe Separation Angle 116.5°

LT1 Cam Specs
Part Number 12629512
Duration @ .050 in. (int./exh.) 200°/207°
Valve Lift (int./exh.) 0.551 in./0.524 in.
Lobe Separation Angle 116.5°

LT2
204 / 219
.551 / .551
Revised Cam Profile And Phasing
Now that the exhaust flows about as freely as the intake, the exhaust valve lift is increased by 1mm to match the intake's 14.0-mm lift, which improves exhaust valve flow rate from 122 to 125 grams/second. Duration is also increased, and the range of authority of the cam phasing is now 62 degrees (though the controller seldom orders more than 50 degrees).

It would be my opinion that power is related to intake duration and lift.

Excellent data here.:happy0180:

So the L86 and LT1 share the same stock Cam...

I wonder why the LT4 cam exhibits a smaller intake lift
What are the advantages of this Cam spec in an FI setup? Vs. the LT1/L86?

The 120 LSA cuts down on overlap, don't want to be blowing boost out the exhaust... bad for smog too.

I think OEM valve springs are very weak, GM wants 200,000 miles out of these so cut down on lift helps the larger intake that is also fighting against boost. Less guide wear too. GM wants to use the SMALLEST cam posible for any HP target, and the least lift. So the Lt4s cam is the most dependable, best on smog for the application, the LT1 cam should make more power.

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!

Same plan here. I am at sea level here. Where are you located?

When do you plan installing the LT4 blower on your motor? Are you sourcing the necessary parts and adaptation elements from ADM or WeaponX?
Who will be tuning?

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.

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.

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.


Price seems good, performance better than stock LT4, looks bad action. It was my first choice.

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.

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?

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.

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.:confused0068: 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)

just to finish up on the LT1 cam vs the LT4 cam. I check the LT5 cam specs and it is a DoD delete LT1 cam. exactly: :confused0068:200 /207 .551 / .524 LSA is 116.5
http://www.superchevy.com/how-to/eng...ed-c7-zr1-lt5/
So the LT1 cam is a better factory performance blower cam.

oldman: Verrry interesting...would not have guessed. Thanks for posting.

Well you would actually be amazed on how much air you can push threw this blower with a great set of heads, cam and great tuning. Currently the FASTEST stock blower (ported) LT4 camaro is this yellow ZL1 that CURRENTLY runs a worlds best time of 9.37. AMP with all their air flow technology managed to get over 20 PSI using the STOCK intercooler.

https://www.facebook.com/AdvancedMod...type=3&theater

wow on that little blower...

Well yea - its 20lbs of boost, with a ton of meth and a ice box for the intercooler to chase the heat away.

I run a Alky meth kit and think it is definitely the way to go, especially with a PD blower, but when the sun goes down - the pump is just a $35 motor from a jacuzzi. If you are that meth dependent, it is a grenade waiting to happen.

So bottom line, when remaining on 93 straight from the pump (not even a slight bit of E in my location), I would not run any higher boost than 9 lbs considering that the fueling is LT4 End-to-End as well (Low side to High side, via Injectors, using the LT4 HPFP hard pipes as well).

Well first of all, I mentioned it runs the STOCK intercooler. This car was set up to make a world record and it did yet it still can be driven as a daily driver. Car has made over 200 runs so it is NOT a grenade waiting to happen. Who gives a shit anyway WHAT it takes to make the car go this fast. The fact is it is a world record holder and is unbelievably consistent.

Hey - the post on facebook says it has a icebox for the intercooler - so check the source. The ZL1 I/C isn't known to be a point of concern as long as there are better bricks used in the blower

20lbs on the 1.7 makes a tremendous amount of heat. They are chasing the heat away with the meth and the ice, but it is not a setup you can rely on under boost on the street. On the track where there is a lot more predictable variables it can be planned for - but you will need to put a meth pump in that thing on a regular basis to make sure you dont grenade it.