Mast LS7 SS 675hp Aggressive Street Usage?

[rusreus2]

Hello everyone,

I am looking for some advise on how far I should go with my LS7 and horse power for street usage.
I am planning on buying a Mast LS7 and am trying to determine if the 675 HP motor is going to be too radical for street driving.
Would I be better off to tame the motor with a slightly milder cam for street-ability?

I live in Arizona where it is pretty flipping hot 8 months out of the year. We do not have 93 octane fuel available so guys are mixing 91 and 100 together or are using an additive.

My project is a 69 Camaro that I have put the DSE sub frame, 4 link and frame connectors under. I am utilizing a Tremec 6 speed magnum transmission and ford 9" rear end with 389 gears. She is going to be cooled by a Ron Davis dual fan radiator and stopped by Baer brakes assisted by Hydra boost.

I am hoping to build a car / motor that I can drive and enjoy without having to work on or tear done every few months. I am just trying to make sure that i am not heading into a world where you cannot have one with out the other. if so, how far do I have to back things down to get a balance.



I am open to suggestions and advise from those that know more than I.

Thank you,

Darwin

[mean buzzen half dozen]

I would go with a supercharged LS engine, once you go supercharged you will never want a N/A engine ever again.

[Cobra 498]

I would go with a supercharged LS engine, once you go supercharged you will never want a N/A engine ever again.

Except after doing a few track laps and the intake air temperature goes over the moon and you have to dial it back. My 4.0 liter Whipple on 5.4 Mod engine with inter cooler and big radiator is good for no more than 3 hard laps at Willow Springs on an 80 degree day. I Have heard the 2015 Z06 has similar problems in hot weather.

[72BBSwinger]

I run a .600/.600 247/255 cam in my car and it is kitten enough for me. Don't know how much cam that one needs to make 675hp but I bet it isn't to much bigger than mine. Heat can be controlled with the tune.

[sheck44]

Darwin, whats the intent of the car ? Street, track etc ??
After looking at some vids of that motor I personally think that would make a great street car motor !

Cheers
Steve

[mean buzzen half dozen]

Except after doing a few track laps and the intake air temperature goes over the moon and you have to dial it back. My 4.0 liter Whipple on 5.4 Mod engine with inter cooler and big radiator is good for no more than 3 hard laps at Willow Springs on an 80 degree day. I Have heard the 2015 Z06 has similar problems in hot weather.

There is more than one way to supercharge an LS, it does not need to be a roots type blower with water cooling.
Turbocharging, IMO, is a better option to supercharge.

When your blower gets heat soaked then it's time to install a methanol kit.
It will drop down your intake temps below ambient temps.
On my truck I boost to 24-25 PSi & will see intake temps in the 60's on a 70-80 degree day.

http://www.alkycontrol.com/

Not sure you are interested, but my,,,

my friend used to make kits to supper chill your intercooler water by using your A/C system.
http://www.fordf150.net/photos/membe...iller-box.html
http://www.f150online.com/forums/lig...ller-data.html

I believe he still has all the parts to make them in stock.

If you had a choice, would you rather have your 5.4 naturally aspirated?

[rusreus2]

Sheck44 / Steve.

I am planning on 85% of my driving to be street usage. I would like to get it out on the track some too but that is not a guarantee.

I am trying to make sure that I am putting a healthy combination together that will still allow me to enjoy her on the street and driving her to car shows.
I am a little concerned about the aggressiveness of the cam and head combination for street cruising. Also, we do not have 93 octane fuel available and I want to make sure I am addressing
this issue proactively.

D

[rusreus2]

Sheck44 / Steve.

I am planning on 85% of my driving to be street usage. I would like to get it out on the track some too but that is not a guarantee.

I am trying to make sure that I am putting a healthy combination together that will still allow me to enjoy her on the street and driving her to car shows.
I am a little concerned about the aggressiveness of the cam and head combination for street cruising. Also, we do not have 93 octane fuel available and I want to make sure I am addressing
this issue proactively.

I prefer to keep the motor naturally aspirated.

D

[sheck44]

Now I'm no expert but at a CR of 11.4:1 on that motor would require 93 at a minimum .. I'm sure someone will answer this
Not having access to 93 may dictate your motor of choice
Now I have an aggressive cam in mine, the car actually shakes from side to side like my big block, but as for ease of driving ... my wife could drive it easily (she won't though lol), these LS motors are soooo streetable and btw, my car is the same .. it's a street / show car

Cheers
Steve

[MattG]

Just a thought...Mast will make you any motor you want with Any amount of power you want and they will charge a Large sum to make it for you. You can buy a LS7 crate motor from GM and put the Katech Torquer cam in it and make the same power with better torque. I had this combo in my last car and with a ported stock intake, cam and springs from Katech and I put 650 to the rear wheels. It drove great for street use (a great tuner is a must) and never dropped off in high end power. Go to the C6 Z06 Corvette forum and you will be amazed what that crate motor can do (at 2/3 the price).

Now if you sent the heads to WCCH and let them do there magic, get a Mamo ported Fast intake and the latest version to the Katech Torquer, you will be Over 600 RWHP and still be way ahead as far as cash output. Last but not least the dry sump is a nice piece of mind for road course events.

Lots of options for you, this is just my real world experience...

Matt

[71RS/SS396]

Are you using the close or wide ratio magnum trans? Will you be doing highway driving where you will be using 6th gear?
It's pretty hard to know if the engine will have decent street manners without the cam specs. If the cam is too aggressive it will render 6th gear useless until 80 plus mph and it will likely surge and buck in any gear at low rpm.
I'm with MattG on this one, for what you want to do with the car I would buy a crate from GM and do a cam swap. You can get to 600 hp with a fairly mild cam that will have good street manners and still be easy on the valvetrain parts.

There's a few things that stick out to me in that Mast build sheet, 1) 39 lb/hr injectors are too small to support 675 hp 2) they list a 4.125 bore but claim they hone the block, problem is that's the stock LS7 bore size so how are they honing the block?

[Trevor @ Texas Speed]

As you've probably found out, everyone has a different method of reaching an end goal. This is no different. I do agree that once you have a supercharged setup you'll never want anything else. Ask me how I know! The best part about supercharged setups is that you can keep the setup really tame and still make killer power. No matter who builds it, any 675 HP naturally-aspirated engine is going to have a cam that's more on the aggressive side. Our TSP 427 LS7 675 HP package has 11.45:1 CR and a 242/250 duration cam. It can most certainly be driven on the street, but it's an aggressive cam. So, it's not going to like cruising down the road in 6th gear at 1,400 RPM. You'll get some bucking at the lower RPM's. Again, this doesn't matter who supplies the engine. Cams with a certain amount of duration are going to be fairly predictable in how they drive. With your high ambient temps in AZ and your concern regarding streetability, I think you'd be better suited for something a little lower in compression ratio with a smaller cam. I'd venture to say that 95% of our turn-key engines ordered are customized in some way, whether it be someone wanting to change the CR, camshaft, rotating assembly, etc. So, we could set you up closer to the 11.1:1 CR range with a moderate-sized cam that will drive great and be more pump-gas-friendly. We could get you right around the 650 flywheel HP mark with exactly what you want, and you won't have any regrets on the setup. You can see the two 427 LS7 turn-key packages that we offer in the link below. We would essentially build you a custom setup that would put you in between the two listed:

http://www.texas-speed.com/c-2213-ls...-packages.aspx

The last thing you want is to survive a car build, finally get it up and running, and then not be pleased with the end result. I've been there and done that, so I understand where you are. We can also custom-tailor the cam to work well on a road course, in case the car ever does see some track time. The larger cams aren't going to be ideal for any road course since they're going to make their power further up in the power band. You also have to keep in mind that due to the design of the LS7 heads, they are very rev-happy. So, the larger duration cams are going to want to see close to 7,000 RPM to take advantage of every last ounce of HP. A more moderate cam will provide you with a much more usable power band, both on the street and the track.

Feel free to give us a call if we can help. FYI, all of our harnesses are also custom-built by Speartech for each application that will still use a MAF sensor and O2's for factory-style driveability!

Thanks!

Trevor
Texas Speed & Performance