DaleTx

Thanks.... can't wait to do some more runs this afternoon!

Che70velle

iTrader: (6)

Yeah, let us know how it goes!

DaleTx

I spent part of the day Friday with Brian at Nutter Racing Engines to watch some dyno pulls on my new engine, and to help test the different cold air intake set ups I had built. I wanted to find out how the cold air intakes performed to help decide which set up to use in the car.

By the end of the day Brian had the tune dialed in! The baseline tune was done using a speed density tune with an open 4 barrel TB (no air intake or filter setup). The tune came out great and the engine ran strong!

Here's a recap on engine details:

427CI LS2, 4.125" bore x 4.000" stroke
GM LS7 single plane intake with port fuel injection setup (58# injectors)
Fast 4 barrel TB
GM LS7 heads,CNC ported,titanium intake valves,T&D 1.8 rockers
Custom CAM, 247/255 @ 0.050 112 lobe separation
Forged crank and forged pistons, ~11.5:1 compression
NRC 4 stage dry sump oil pump
GM CTS-V fuel pump (380lph) with Vaporworx digital control
fuel pressure 58psi
fuel for test, Chevron 92 octane pump gas

Here are the dyno results and a couple of graphs:



I was very pleased with the results! this is exactly what I was looking for. The LS7 heads were impressive. They just flat performed from low rpm all the way up. We ran it up to 7,200 to 7,400 all day long with no hint of valve train instability.

Now on to the big suprise!

When we bolted up the 90 degree elbow on the throttle body and made a pull the peak Hp dropped by 70!!. The peak Hp was only 598.

Next we bolted on the homemade snorkel set up. Peak Hp was down by 35. The peak Hp was 635..... not as bad but still not good.

For the last test we put on a 14" round air filter with a 4" wide K&N element. The peak Hp was 660.... we only lost 10Hp, not bad. I'll give up 10 Hp but not 35 or 75!

At this point the elbow is going on the shelf. I learned that the elbows do not work well on a naturally aspirated set up. I knew going in that elbows are mostly used with boosted engines now I know why...they need a head of pressure to work properly (my educated guess).

Lastly.... the CTS-V fuel pump and Vaporworx controller worked flawless. The idea of this setup is that the voltage to the pump increases or decreases depending on the demand for fuel from the engine. When my engine was at idle the controller was putting out 7 volts to the pump. When the engine was wide open at 7,200 RPM the controller was putting out 10.9 volts. I know now that this set up easily supports 670 Hp.

The other advantage of this set up is there is no return line so the fuel is not constantly recirculating and heating up. Cooler fuel, more power... good in my book.

Here are some pictures of the cold air intakes and the fuel tank set up I was talking about.




On monday I'm going back for some more dyno runs and I will take a video to post up on youtube. I was amazed to hear this engine run.... it was so smooth and revved so effortless. I can't wait to get it in the car!

Cheers!

ringram

Intake looks nice, Im wondering if you are compromising design a bit by retaining the maf. You should be able to fuel fine without it and perhaps even obtain better throttle response.

If the intake design would be similar either way then cool. SD does not restrict your intake design.

DaleTx

That's true, I was trying to design the cold air intake to accommodate the MAF sensor which is calibrated for a 4" (100mm) diameter tube, and I was trying to keep the volume in the chamber down. I didn't realize that a speed density tune could provide better throttle response. Thanks for that bit of information. All the the engines I have done in the past have been carburated.

For the next step I will design a new cold air intake that has more volume at the throttle body chamber, and less restriction where the tube connects to the chamber. I will design the intake to allow better airflow, and plan to test with a SD tune.

sixt9er

iTrader: (2)

What pistons (part number) are you using for your build? I, too am working on a project similar to yours, for my 1969 Camaro. My project includes a dry-sleeved, LS2 block, CNC-ported L92 heads, Pat G. Spec cam, looking to purchase a 4.0" stroke crank shaft. It will be a 427 CID engine, with a Edelbrock Victor Jr. 4 bbl intake, with a 4150 type throttle body on top.

machinistone

Depends upon what you want your final compression to be, he used the K463X125 pistons which are a -2.8cc, I have a dry sleeved 427 going together that we're using either those or the K395X125 pistons on which are -8cc depending upon the final chamber cc and deck height as there's also a .005" diff. in compression height.

DaleTx

We used Weisco forged pistons part number K463X125 as posted by machinistone. My engine is set up for ~11.5:1 compression ratio. The crankshaft is a Manley LS Pro Series light weight forged crank. The crank is set up for a 24 tooth reluctor. The connecting rods are Manley H-beam.

Good luck with your build.

obZidian

iTrader: (2)

Not bad... 500rwhp++ is a good start.

Any pics of the engine in the car?

DaleTx

The engine is still on the dyno today. I'm going to test one more cold air intake if time allows.

Pumba

Great Job with your build and the testing you did on the dyno!

One thing I would talk to your dyno operator about is the correction factors that he applied to your power run. SAE has not used a barometer of 29.92 inches of Mercury and 59 degrees F since 1989.

Today's SAE correction factors are 29.53 inches of Mercury at 77 degrees F.

DaleTx

Thanks for the compliment.

I was happy with the results of the build when looking at the numbers and the graphs. The Hp curve was very linear and smooth from the bottom all the way up to the 7000+ RPM range. The torque curve looked good also... the torque held on a long time and was still over 500 lb-ft at 7000 RPM. The engine idle was set at 1050 RPM and sounded sweet! Bryan said this engine would idle below 1000 RPM with no problem. I am very happy with the engine builders cam choice

Engine build specs:
427 CI LS2, 11.5:1 compression, CNC ported LS7 heads, LS7 single plane intake with port fuel injection, 4 barrel TB, cam 247 255 @ 0.050, 112LSA, 4 stage dry sump oil pump.

Final results (92 octane pump gas):
Peak Hp: 672 @ 6900 RPM
Peak Torque: 566 @ 5500 RPM

Avg HP: 610 (4800 to 7100 RPM)
Avg Torque: 540 (4800 to 7100 RPM)

I have an interesting engine comparison I will post up tomorrow. The same cam listed above in a 427 CI LS2 with hand ported LS3 heads, LS intake, and slightly higher compression (over 12:1). This engine was built before mine and went into a full time race car.....

dr ls7

Did you get to try 1 7/8in or 2 in headers

DaleTx

I have not been able to test the 1-7/8” headers yet. Yesterday we did more pulls with the 1-3/4” to 1-7/8” stepped headers. The next engine to go on the dyno is waiting for a wiring harness so I might have more time. If I have a chance to test the 1-7/8” headers I will. That would be a good test to see if there is a difference.

Right now I’m thinking about what setup to use for the cold air intake. The elbow is out…. my home made cold air intake worked pretty good but still restricted the airflow quite a bit. Any ideas for modifying the design of the cold air intake? Thoughts on MAF tune vs SD?

briannutter

Stout numbers! that thing pulls long and wide. You're going to have to get used to shifting at 8000rpm!

AC Nutter is cool as hell. We've always joked about him being my long lost uncle. Then found out his son is named Brian. What are the odds of having two Brian Nutters doing LS development?

DaleTx

Well I finally figured out how to post videos.

Engine dyno video.... open 4 barrel throttle body, 3500 to 7300 RPM.

https://www.youtube.com/watch?v=9vfKPg3rElM

I am in the process of trying to modify the homemade cold air intake to get more airflow. I'm planning to give up on the MAF setup and use SD tune.

DaleTx

Hey Brian Thanks....I remember meeting you a couple of years ago at SEMA. You had your corvette down there running in the optima challenge I think. We talked about some pistons.
Yeah AC is very cool... It has been a great experience working with him!

DaleTx

When I first started my build I wasn't sure if I wanted to use an LS intake with mono blade throttle body, or go with a single plane w/4 barrel throttle body.

I ended up going with the single plane w/4 barrel throttle body to try something different, and I knew I could get the higher RPM and Hp I wanted.

For anybody trying to make the same decision here is a comparison between my engine with the single plane intake, and another engine with the LS intake. both engines are 427 CI (4.125" bore x 4.0" stroke) and we both used the same cam. The LS intake engine was built just before mine in the same shop. I asked for a printout of dyno numbers so I could compare the setups and learn something.

It's not complete apple to apple comparison... the bottom ends were similar but mine had CNC ported LS7 heads 11.5:1 compression and the other engine had hand ported L92 heads and slightly higher compression (over 12:1). Both engines used the same cam though: 247/255 @ 0.050 112 LSA.

Here is the results:

427 with LS intake (numbers and graph)




427 with single plane intake (numbers and graph)


Same cam, way different results. These engines would have completely different feel in the car. For me the higher RPM and Hp is a good fit for what I want to do with my car.... manual trans, 3:73 rear gears, 3400 lbs, driven on road courses (track day events).

Bryan0092

Great write up Dale.

DaleTx

Thanks!


I plan on picking up the engine this week if all goes well. The engine testing and tuning is done. The only hold up is the engine builder is waiting for my custom wiring harness to come in. They want to test the harness before I pick up the engine. This weekend I started getting things ready for the install so I’ll be ready to go when the engines done. The engine is out of my car…I just need to get the wiring in order and start planning for the plumbing for the dry sump pump and tank.

Since I am increasing from 450Hp to 670Hp I had to make other changes to the car to make sure everything is sized to handle the extra power. For the clutch I decided to go with a Corvette ZR1 twin disc clutch and an aluminum flywheel. The aluminum flywheel offsets some of the extra weight of the ZR1 clutch. The clutch has been modified to increase grip 20 percent over stock. This clutch should be good for well over 800Hp. I have read good reviews on this set up…. we’ll see… I’ll put it to the test

The twin disc clutches I’ve used in the past worked good on the street, but they didn’t hold up very well with any abuse. If the clutch got overheated even once, the floater discs warped. When the disc warped then the clutch would lose grip and not disengage properly. I’m tired of fighting the clutches so this time around I spent the extra money for the ZR1 clutch. The floater disc in the ZR1 clutch is 3 times thicker than my old clutch (old floater disc ~0.25” thick, ZR1 floater ~0.75” thick). I don’t think this one will warp. It’s hard to beat the OEM stuff.

Here's a few misc pictures of the car, the old clutch, the new clutch, and flywheel.



aluminum flywheel


Looking forward to putting the car back together.... once I get the engine things should go pretty fast