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Old 06-11-2008, 12:20 AM   #1
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355 Vortec LT4 Hot Cam Engine Build - With Dyno Results

Since this is a pretty popular combo and can be done very cheaply, I thought I'd post up the results of my recent engine build.

Specs:
Block: 350 2-bolt main from 1990 C1500 (free - Dad's old engine)
Crank: Cast 3.48" stroke from C1500 (free)
Rods: SCAT forged I-beam 5.7" ($200)
Pistons: Clevite/Mahle claimer hypereutectic ($75)
Rings: Hastings moly ($35)
Bearings: Clevite (free - Dad's extra set)
Oil Pump: Melling 55HV (Free - Dad's spare)
Heads: Vortec 906 casting, stock 1.94" I 1.50" E valves, 3 angle valve job ($500 with cam, springs, valve, timing chain and gear, plus misc gaskets)
Camshaft: LT4 Hot Cam 218I/228E @ 0.050" lift
Lifters: Melling hydraulic roller - stock replacements ($100)
Pushrods: GM PN 12371041
Valve springs: LT4
Rocker arms: Stock self-aligning 1.5:1 ratio - from C1500
Intake manifold: Edelbrock Vortec Super Victor ($150 - used ebay)
Carb: used multiple carbs during testing - best results with 750 demon, mechanical secondaries
Ignition: Accel large cap HEI with cheap 7mm plug wires
Fuel: Shell V-Power 93 Octane and Shell 87 Octane (made same power)

Machine work:
$150 for boring the block 0.030" and pressing the pistons on the rods and installing new cam bearings.

Assembly:
I assembled the short block at home over my winter break from college. I finished the job at school in my dorm room.

The engine actually turned into a school project. We were recently donated a piece of software called Wave by Ricardo that is used by most of the major OEMs to model engines before they are built, as well as to find potential performance improvements. I took data and measurements on the engine to be able to create a model to compare to the actual dyno results. In the end, they turned out pretty close even without any tweaking to the model. If you are curious about the program, send me an email and I'll pm you with details, but unless you have an extra $30k lying around, forget about being able to use it.

Head Flow Data:
Performed on SuperFlow 600 Values in CFM @ 28" of H20
Intake Exhaust
.1 63.7 48.3
.2 122.4 98.3
.3 179.4 128.4
.4 218.9 144.2
.5 236.2 152.2
.6 223.1 153.7

Dyno Performance:

Peak Power (SAE Corrected) was 362.3 hp @ 5800 rpm
Peak Torque (SAE Corrected) was 366.1 ft*lb @ 4400 rpm

Graphs and Tables below.

Last edited by rhit_rs; 06-11-2008 at 12:32 AM.
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Old 06-11-2008, 12:30 AM   #2
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Re: 355 Vortec LT4 Hot Cam Engine Build - With Dyno Results

dynoresults.jpg - this should be a link to the dyno graph

I'll post the data from the dyno tomorrow along with the prediction from the program. If you have any ?'s, feel free to ask.

Since I was hoping for a little more than 360, I'm planning on switching to 1.6:1 roller rockers. I'm also thinking about doing a little port work on the heads, but nothing too crazy - just a little cleaning up.
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Old 06-11-2008, 08:43 AM   #3
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Re: 355 Vortec LT4 Hot Cam Engine Build - With Dyno Results

Quote:
Originally Posted by rhit_rs View Post
Attachment 158520 - this should be a link to the dyno graph

I'll post the data from the dyno tomorrow along with the prediction from the program. If you have any ?'s, feel free to ask.

Since I was hoping for a little more than 360, I'm planning on switching to 1.6:1 roller rockers. I'm also thinking about doing a little port work on the heads, but nothing too crazy - just a little cleaning up.
Have you calculated your static compression ratio and dynamic compression ratio? This combo is very similar to my own and your results are very interesting.
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Old 06-11-2008, 12:52 PM   #4
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Re: 355 Vortec LT4 Hot Cam Engine Build - With Dyno Results

Quote:
Originally Posted by rhit_rs View Post
Attachment 158520 -

Since I was hoping for a little more than 360, I'm planning on switching to 1.6:1 roller rockers. I'm also thinking about doing a little port work on the heads, but nothing too crazy - just a little cleaning up.

You gotta work those heads to get more air in. I did a 355 with a comp xr 264 that we are playin with and we picked up 30 horses by working the vortecs and retarding the cam a bit.
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Old 06-11-2008, 01:14 PM   #5
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Re: 355 Vortec LT4 Hot Cam Engine Build - With Dyno Results

Thank you for posting the results and engine information. I assume this was on an engine dyno? You got over one horsepower per cubic inch.
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Old 06-11-2008, 07:42 PM   #6
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Re: 355 Vortec LT4 Hot Cam Engine Build - With Dyno Results

The static compression ratio came in at 9.8:1. The pistons were .032" in the hole and the head gasket was 0.028" compressed. The vortec heads have 64cc chambers. I haven't calculated the dynamic compression ratio, but the intake valve does not close until 78 degrees after BDC, so it bleeds off quite a bit at low rpm.

Here's the power and torque plot from the Wave model:
waveresults.jpg

And here is a comparison of the two:
comparison.jpg

For those of you who like looking at the actual dyno data data:
run21_ignrelay.zip - notice the VE is up over 100%. The bsfc numbers were decent, but I'd like to see a little better. A hotter ignition system might have helped power a little.

The dyno results came from running the engine at a 200 rpm/s sweep on a SuperFlow 902.

Last edited by rhit_rs; 06-11-2008 at 10:54 PM. Reason: Dyno details.
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Old 06-11-2008, 07:50 PM   #7
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Re: 355 Vortec LT4 Hot Cam Engine Build - With Dyno Results

Double post.

Last edited by rhit_rs; 06-11-2008 at 07:51 PM. Reason: Glitch
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Old 06-11-2008, 10:18 PM   #8
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Re: 355 Vortec LT4 Hot Cam Engine Build - With Dyno Results

Ya know, that LT4 Hotcam was designed to be used with 1.6 rockers. Your max lift with 1.5s is only .490 and it also mellows the whole lift curve a little everywhere. Would be interesting to see what you might pick up using the 1.6 it was designed for, if you've got the guide clearance and springs to handle the .525" lift that would net you.

I'm also thinking that Super Vic is probably way too much manifold for such a mild sub-6000 RPM combo. I bet you'd pick up quite a bit through the midgrange with a Performer RPM dual plane or similar.

I doubt your Accell HEI ignition system is giving up much power to a CD box at this point.

Some ideas to consider for "round 2" of the school project!
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Old 06-11-2008, 10:52 PM   #9
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Re: 355 Vortec LT4 Hot Cam Engine Build - With Dyno Results

I do have clearance to run the 1.6 rocker arms. I'll be putting a set of those on before it goes in the car.

You can see on the graphs where the manifold starts to go into its working range at about 3000 rpm. I don't think it's quite as much overkill as some might think. The runners are actually longer on the Vortec Super Vic than on the standard SBC Vic Jr, lending to better low rpm performance. I was surprised by what I found when I made the measurements. I am going to run a dual plane when it first goes in the car (hood clearance issues). Eventually, I'd like to convert the super victor to port fuel injection.
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Old 10-21-2008, 04:36 PM   #10
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Re: 355 Vortec LT4 Hot Cam Engine Build - With Dyno Results

rs,

I agree that you should be using 1.6s with that cam. I sold my vortec heads to mkros1980 and he ran it on his boat motor with the lt-4:

Quote:
396HP 449TQ at the fly with the Edelbrock 600CFM Marine carb and wet manifolds. I pulled the entire motor for the winter to paint the bilge and redo the rigging and took the motor up to my buddys shop for a quick dyno.

Last run on Sunday. http://www.youtube.com/watch?v=L8YRUMqqDEI

64.1MPH

Vortecs and the LT4 cam is a SOLID performer
He ran 918 beehive springs and did not have to worry about valve guide clearance due to the 918 retainers. If you run regular springs, you would have to cut down the guides.
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Old 10-21-2008, 04:44 PM   #11
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Re: 355 Vortec LT4 Hot Cam Engine Build - With Dyno Results

This thread is GREAT! I have almost the same combo as you I WOULD REALLY BE INTERESTED IN THE RESULTS OF THE DIFFERENT CARB TESTS!

I ask because im runnning a holley 3310 vs and I wanna go to either a 650 or 750 double pumper or 750 eldebrock.

My combo:

355- speed pro flat tops shot peened rods floating wrist pins cast crank
Vortec heads with 1.6 roller rockers
LT4 "hot cam"
Eldebrock performer RPM intake
holley 780 VS carb
HEI ignition


Chevy high performance did a buildup here were their "results"

http://www.chevyhiperformance.com/te...ild/index.html
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Old 10-21-2008, 08:02 PM   #12
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Re: 355 Vortec LT4 Hot Cam Engine Build - With Dyno Results

Quote:
Originally Posted by Rayzor32 View Post
....Chevy high performance did a buildup here were their "results"

http://www.chevyhiperformance.com/te...ild/index.html
Here is their single-plane manifold with NO carb spacers.
Click the image to open in full size.
Does y'alls look like that?
Yeah, that'll fit under a stock hood with an air cleaner.
And that was before they added a 1" spacer and a 1/2" spacer.
...must be nice to build engines that won't have to be under a HOOD!
p.s.I think the picture of the dyno screen was before they brought out the 1-1/2" of spacers: 356hp@5700... a little more like real life.
rhit_rs: excellent post with real world data, congrats!
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Old 10-21-2008, 08:11 PM   #13
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Re: 355 Vortec LT4 Hot Cam Engine Build - With Dyno Results

yeah and in the pic with the dual plane it has 2 carb spacers on it and they say it made 412hp at 5700rpm. wtf are car mags always using carb spacers and demons they must get them for free. And then the dyno screen shot wtf?
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Old 10-21-2008, 08:22 PM   #14
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Re: 355 Vortec LT4 Hot Cam Engine Build - With Dyno Results

Quote:
Originally Posted by TheBadazz View Post
You gotta work those heads to get more air in. I did a 355 with a comp xr 264 that we are playin with and we picked up 30 horses by working the vortecs and retarding the cam a bit.


how much did you retard the cam? did you use a degree wheel or just the +/- marks on the timing gear
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Old 02-03-2009, 03:56 AM   #15
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Re: 355 Vortec LT4 Hot Cam Engine Build - With Dyno Results

Rayzor, thanks for posting the link with Chevy Hi's build.

In truth, I basically copied that engine. Same heads, intake, carb (while it was on the dyno), cam, C.R., etc, etc. I actually have the article in a book chevy hi published titled "Small-Block Chevy Engine Buildups." It has a bunch of great builds from over the years. Anyway, when the engine was on the dyno I kept kicking myself wondering where they got the extra 70 hp over what I was seeing. I only ran stock 1.5 rockers, but I know those aren't leaving 70hp on the table. After looking at the picture, I'm still wondering where they got the extra power. I ran a 1" spacer at times as well (it picked up a few hp on the top end). I'm going to call or email them about the discrepancy. There are some tricks with which test you run on the dyno that can make a difference. They also ran an electric water pump (as shown in only some of the pics...others have a mechanical), which saves a few hp. But clearly on one test they only made 356hp...magazine voodoo. In hindsight, I would have liked to put the 1.6 rr's on and an electric water pump to do a true comparison. Also, I was running 200rpm/s sweeps, not step tests which let the engine stabilize. This factors out the energy required to accelerate the rotating assembly, including the flywheel. I'm guessing Chevy Hi did a step test. I'm guessing they also multiplied the power by the STP Correction Factor (apparently 1.119 that day). 356hp * 1.119 = 398hp Add a spacer and you're there (at least for the dual plane). Maybe I should have tested on a hotter day to get a better correction factor . I really wish they'd post all of the dyno data up...i'd be nice to see some bsfc numbers on their engines.

The heads I bought already had the machine work done to them to allow the LT4 valve springs to be used. When I put them together I verified that 0.525" lift would not be a problem.

I did run a couple different carbs. The holley 650 vacuum secondary and the 850 double pumper both made about 355hp, while the demon picked up about 10hp putting it at 365hp. I'd have to check the dyno data, but I remember the demon carb having a decent amount less manifold vacuum at WOT than the 650vs & 850dp. Both holley's had a little more restriction. If you look at the two vs the demon, it's clear why...no choke and very smooth entry through the throttle blades.

An update on the engine:
I put it in my car (92 RS), mated to a WC T5 from an 88 v6 car (4:1 first gear is crazy), at the end of the summer before I went back to school (a story in itself!). I had to use a mercury marine tbi to vortec intake manifold for hood clearance issues. I'm using a holley throttle body with a gm injector pod on top and 61#/hr injectors at 30 psi. I've tuned it enought to make it drivable (using ostrich and TunerPro RT), but it still needs some work. I've been short shifting it at 5k since I'm afraid of running it lean with the small injectors and a lack of a wide band to tune it with. I've done a couple autocrosses with it, and man, what a difference from the old LO3! I've also taken it out to a couple track day sessions at putnam park. Passing a few mustang GT's with the new engine was very gratifying! I still haven't put 1.6 rr's on yet. That'll happen sometime this summer. Right now I'm still working on the tune and cold weather driveability. Here's the finished product in the car:

Click the image to open in full size.

Hopefully this thread has been informative. If you have any questions on my setup feel free to post here or send me a PM. Long live budget SBC's!
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Old 02-03-2009, 12:40 PM   #16
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Re: 355 Vortec LT4 Hot Cam Engine Build - With Dyno Results

Hey rhit_rs, that's a nice build and good results. I'm a 1982 ME from Rose. Your rhit name immediately caught my eye.
Did you degree the cam? Installed "straight up", just going by the index marks that Hotcam would fall in at 109 deg ICL if all stackups are at nominal. That's great for roadracing, which is what they designed it for. But for better low/midrange torque, driveability and mpg, some have been installing it at 107 ICL and not even seeing a hp falloff up to 6000 rpm. I'm just thinking that you might not like the powerband as much as you do now if you step up to the 1.6 rockers. The overlap area goes up significantly. If the cam is in fact near 107 ICL, then I'd say the 1.6's are a good idea.
Putnam Park, eh? I love that place. I've run my 96 ImpalaSS there a few times.

Pat

Edit: I'm also thinking about your CR. That Hotcam with the 1.6's would probably like a little more. If you ever pull the heads, consider going back together with .015 steel shim gaskets. They would tighten up your quench and you wouldn't take a hit on detonation resistance. I assume your pistons are the typical rebuilds that sit a little deeper in the hole than stock. Flat tops with the 4 valve reliefs?

Last edited by 86LG4Bird; 02-03-2009 at 12:45 PM.
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Old 02-03-2009, 04:06 PM   #17
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Re: 355 Vortec LT4 Hot Cam Engine Build - With Dyno Results

Quote:
Originally Posted by rhit_rs View Post
Anyway, when the engine was on the dyno I kept kicking myself wondering where they got the extra 70 hp over what I was seeing.

I've enjoyed your posting and I thought I might comment.
You're right on with the electric water pump and the horsepower gain.
One other thing to consider is the type of headers the magazines are using. It's plain to see in some of the articles that they've taken the time to determine optimal collector lengths in order to gain the benefits of exhaust pressure wave tuning.
There can be quite a difference, maybe as much as 25% or more, between a well designed system and something put together of the shelf.

Last edited by five7kid; 02-03-2009 at 05:40 PM.
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Old 02-03-2009, 07:11 PM   #18
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Re: 355 Vortec LT4 Hot Cam Engine Build - With Dyno Results

Pat,

Look for a PM from me.

I did install the cam straight up. I just used the plain GM timing chain set. I did profile the cam for the purposes of inputting the data into the model and it looks to be at 108 degrees, but that's probably only accurate to a degree or two. On pretty much all of the dyno runs, peak power occurred at 5700 rpm, right where I was expecting it based on chevy-hi's results. Admittedly it is a bit peaky, but I can live with it. With the ratio's in the v6 T5 (4.07, 2.18, 1.56, 1, .78) and a 3.23 rear it's not too hard to keep the engine up where it's happy. I've been getting around 20 mpg at cruise running a little over 70 mpg at 2200 rpm.

I realize the duration at 0.05" will go up some with the roller rockers, but I'd like to find out what kind of gains they'll give. I'm planning to G-tech the car before and after the swap, but that won't be until sometime in the summer.

As far as the CR goes, you're probably right. With a little more overlap from the 1.6's I could probably bump it up a little. The pistons were down in the hole about 0.020". Yeah, flat tops with 4 reliefs. The're hypereutectic claimer pistons from clevite/mahle. I could use a little more quench. I've thought about running 87 in it, but 93 is cheap insurance against knock. Once I get the tune a little better I might play with running it on 87. I do have a 2Timer from moates.net that will let me run two different chips. I could back the timing off a little and make one of the settings the 87 octane one.

I do love Putnam Park. I've done a track day and a half there. The first one was last summer with the old engine and trans. I was slow, but it was still fun. I think I had 3+ hours of actual on track driving that day. The second time was this fall. My parents were actually there doing a track day and I was just visiting and riding with them. My father's kit car blew 3rd gear out of his T5, leaving an open spot for me to do a couple of sessions. What a difference twice the power and a manual trans makes! Are you planning on heading over for any this year?
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Old 02-03-2009, 07:15 PM   #19
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Re: 355 Vortec LT4 Hot Cam Engine Build - With Dyno Results

Quote:
Originally Posted by skinny z View Post
I've enjoyed your posting and I thought I might comment.
You're right on with the electric water pump and the horsepower gain.
One other thing to consider is the type of headers the magazines are using. It's plain to see in some of the articles that they've taken the time to determine optimal collector lengths in order to gain the benefits of exhaust pressure wave tuning.
There can be quite a difference, maybe as much as 25% or more, between a well designed system and something put together of the shelf.

Good point about the exhaust. The article lists them using hooker 1 5/8" long tubes. They show a picture of the setup. They do have a nice set of merge collectors on the headers. I used a set of 1 5/8" long tube heddmans. They look similar, but the collectors weren't as long. Here's a picture of the engine on the dyno:

Click the image to open in full size.
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Old 02-03-2009, 08:21 PM   #20
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Re: 355 Vortec LT4 Hot Cam Engine Build - With Dyno Results

[quote=rhit_rs;4030800]Good point about the exhaust. The article lists them using hooker 1 5/8" long tubes. They show a picture of the setup. They do have a nice set of merge collectors on the headers. I used a set of 1 5/8" long tube heddmans. They look similar, but the collectors weren't as long. Here's a picture of the engine on the dyno:

QUOTE]

Great article about header theory. You may have read it.

http://www.superchevy.com/technical/...exh/index.html

Are you familiar with the Pipe Max program? You can the results of a well designed system.
Collectors like the length in this photo and coupled to the right style of muffler really aids in the pulse tuning of the exhaust to a specific rpm range.
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Old 04-22-2014, 06:53 PM   #21
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Re: 355 Vortec LT4 Hot Cam Engine Build - With Dyno Results

I hate to be a grave digger, but rather than starting a new thread I thought I'd bump this one. I have a 2000 S10 with a 350 Vortec swap and I kept all the computer and EFI stuff. The rod started knocking the other day so I'm going to do a rebuild. Is there any reason I couldn't do this and keep my EFI?
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Old 04-22-2014, 08:17 PM   #22
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Re: 355 Vortec LT4 Hot Cam Engine Build - With Dyno Results

Quote:
Originally Posted by ZQ8 Blazer View Post
I hate to be a grave digger, but rather than starting a new thread I thought I'd bump this one. I have a 2000 S10 with a 350 Vortec swap and I kept all the computer and EFI stuff. The rod started knocking the other day so I'm going to do a rebuild. Is there any reason I couldn't do this and keep my EFI?
I think it would be foolish not to keep the EFI, if it has been functioning already with a Vortec engine.
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Previous: Stock Internal LG4, TPI exhaust, 3.73 Torsen, S-10 TC....
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13.05 @ 104 on the 100-shot

Now: 250k mile L31 motor with new rod bearings, timing set, ZZ3 cam, Performer manifold, and Edge 2800 TC..... 12.91 @ 105.0 on street tires
Still with TPI manifolds and exhaust.
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Old 04-22-2014, 08:21 PM   #23
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Re: 355 Vortec LT4 Hot Cam Engine Build - With Dyno Results

Tuning, basically. Carbs are about 80% self-tuning to the engine they're plopped on top of- change the jets, fiddle with the mixture screws and you'll get it pretty close pretty quick.

When you start changing the engine's basic breathing characteristics with something like a significant change in cam specs, the factory EFI tune kinda goes out the window pretty quick. A custom tune is required to dial it in so it runs well under all conditions, all trottle positions.
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Old 04-22-2014, 09:20 PM   #24
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Re: 355 Vortec LT4 Hot Cam Engine Build - With Dyno Results

Great!

So right now I have a complete 350 Vortec with a knock. Is all I need is a complete rebuild kit, keep my LT4 hot cam, lt4 springs (I currently have LS6, wonder if they'll work?), rods, have it bored .30 over, retune? Anything else?
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Old 04-24-2014, 07:13 PM   #25
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Re: 355 Vortec LT4 Hot Cam Engine Build - With Dyno Results

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Originally Posted by ZQ8 Blazer View Post
Great!

So right now I have a complete 350 Vortec with a knock. Is all I need is a complete rebuild kit, keep my LT4 hot cam, lt4 springs (I currently have LS6, wonder if they'll work?), rods, have it bored .30 over, retune? Anything else?
I'm a bit confused on what exactly you have in the truck now and what you would like to run post rebuild. Are you currently running the LT4 hot cam? Is your current setup EFI? Factory 1996+ port injection efi?

If you are swapping to the LT4 hot cam from a stock or any other cam, as others have said, retuning is necessary for good performance (and driveability). Depending on the size of your current injectors, you might also need to go to higher flow injectors.

Reply with more details and I'd be happy to make more suggestions.

Thanks for digging this back up. I no longer have the car and re-reading was a good trip down memory lane!
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Old 04-24-2014, 07:13 PM
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