403 LS2 FD - LS7 Build for 2020!

[Exidous]

Some good info right thar.

I'm still rocking the stock LS7 crank and rods. The stock pistons will almost certainly be swapped out for forged 4032 pieces to allow a more crap fuel tolerant engine. If that does happen I'll step up to a 4.155" bore and unshroud the exhaust valve a tad. Otherwise it is a tame build but it's all on hold until I get back from my deployment(if I even go). Supposed to be there in under two weeks but still too many unanswered question. If it does happen the car will be sitting until mid winter. :-/ Your car may be LS7 and on the road before mine! Ha

Does Tony really charge $2100 all in for a plastic intake? I think my FAST102 was about $1300 ported from him.

Stock crank and rods for me too, and Mahle low expansion alloy forged pistons.  I have the same alloy in my diamond pistons right now and they're great.  They have some slap when first firing up but they quiet down very quickly.

Yeah I've seen the invoices on corvette forum from Tony..  The intake is $1000, and then porting he's getting like 650 or 750, and then the stealth mod is another 3-400.  And he sells them like candy.

It is easy to be mad at Tony's prices, but gotta give the guy props he is a serious hype man and marketing expert.

Some of that unshrouding you can do in the cylinder head too you can open the chamber wall up around the exhaust port.  Bigger bore is always better though - if you're honing for new pistons you might as well go bigger.

Good luck whichever way your deployment goes.  I'll take it as a challenge to get the engine done if you do haha.

That's probably the same alloy I'm going to use. Not full retard like the 26xx series. I looked at the Mahle pistons but couldn't really find the right relief size and compression height combo. My block was decked to 9.23" when sleeved for some reason so I cannot have the piston proud too much. I've been looking in the 1.165"-1.173" area for CH and the DSS that Summit sells seem to be the only ones that really fall in line with what I need.

I used to have his heads on my LS1. For all the hype and marketing you cannot argue they don't deliver as promised. Never a surprise from him going in if you know what it costs. Aside from it making 50hp more than you were expecting.

I've already played with the bowls a little bit. Once I have the pistons installed and know what gasket I need I'll open up the exhaust side a little. The hard part is holding myself back from going to the 4.185" piston for exactly 0$ extra. I keep telling myself I need to leave space for another hone or two. I'm actually using the power bore sleeves. Made in the USA and can go out to 4.2" if N/A.

Hopefully you'll pull it off. Ha

[MPbdy]

So long as you have the time to wait most piston manufacturers will build you a piston to spec without extra cost, just lead time.

I would be punching that thing out to a 440 real quick   If you hurt a cylinder you'd likely resleeve that one liner vs rebuild the whole thing.  I don't know how often you'd plan to open the thing up to hone the block and replace the pistons but for me that'd be an every 10+ years kind of thing.  With that much use on the engine I wouldn't feel like it owed me anything.  The bad news with an AL block if you seriously lose something in the bottom end the block is going to be toast anyways.  You might as well build what you want.  4.200 sounds cool, but the head gasket is real hard to seal.  Outside of some record setting effort it is probably best to stick with the tried and true 4.185" as the maximum.

Cool about the Powerbore sleeves!  It has been in my head for so long that sleeved blocks = Darton I almost say them interchangeably.  I've seen those on TSP's site.  Their sleeved blocks are super reasonable in price for what you get.

[Exidous]

TSP was where I got mine. It's not been completely smooth working with them as I ordered the block back during Black Friday and am still back and forth with them about a few issues. I'll reserve judgement until everything is settled. Sadly, the LS7 build has been riddled with issues. TSP didn't clearance the block for the 4" stroke despite knowing it was an LS7 assembly. The clearancing looked like something I'd be able to pull off in my garage but I wouldn't have left as much flashing attached to the sleeves. Found ferrous metal chunks in the oil pick up tube. Big enough to get trapped there and with visible tooling marks. My guess is iron shavings from the stock liner removal. The block, pump and assembly are all fine but the bearings all needed replacing after only 100 miles. And lastly, the ICT DOD delete plate. ICT has pretty much written me off and ignoring my emails at this point. They straight up told me that an o-ring large enough to get squeezed out of the seam was completely normal and will seal well.

You're probably right about the 4.185". I have no intention of opening the block up more than mechanical failures deem necessary. The DSS are also an US company and seem to look like a quality product. They run about the same as most other pistons excluding Wiseco. $750 for a forged 4032 set with 1.2mm rings and lighter wrist pins.

[largeorangefont]

Haha my 255's were still hookin after 2 years!  These fresh ones are definitely spoiling me right now though lol.  I've never expected drag car like traction I'm very accepting of black tracking 2nd and hooking 3rd.  I do not expect the LS7 to hook first gear without a drag tire.

I really have been thinking that the ls7 would be too outrageous and make the car into effectively a straight line only machine effectively ruining it.  I've driven the car on street tires where it would roll into wheel spin in third on the highway and you couldn't be confident making a lane change under power let alone powering out of any corner even in 3rd or 4th.  It is comical, but it really isn't fun and I don't care how good a driver you are that will catch up with you eventually.  Sketch on that level becomes unpredictable and there's been a few times it does stupid shit when I'm just trying to drive normal. 

The LS7 will definitely be wild, but I don't think it'll be uncontrollable.  Plus I'm putting a lot of power to the ground with 3.90's.  I could always step down to a 3.73 or 3.55 with the ls7 if I had to, but where's the fun in that 

I'm not trying to be a dick, or talk you out of it, just giving you a counter point.

With the LS7 I think you will look back to the point the car is at right now and say to yourself the car was perfect where it is now.... and it is. The car is still controllable and tossable, and the power delivery is managable, and most importantly you have a little room for error.

Without a widebody, these cars start becoming undriveable as you close in on 550 WHP, and as you are aware will bite you fast if you make a mistake.

I only say this because there have been far too many people with these cars that put too much power in them, and then don't drive them because they are just too hard to balance on the razors edge.

I'd hate to see this thing relegated to drag radials. 

[MPbdy]

It will never be a drag radial only car don’t worry!

No way you’re not being a dick at all. You’re just being honest. I’m pretty pragmatic about the LS7 and how I’m almost only going to make it objectively worse lol and that’s why I’m keeping the LS2 combo going at the same time. The engine build is a dream fulfillment thing and is not exclusively built for the FD, and Texas Mile in this car is kind of like a bucket list deal. Even if I don’t hit 200 running 190’s would still be a hell of an experience.

This is a race engine I’m stupidly putting in a street car and it’s going to be entertaining, probably suck to drive, and be fast AF. For all I know I’m going to get impounded by OC Police as soon as I turn onto the street just for the loud idle lol.

Long term I’ll probably build a mild ls3 short stroke engine for it, put the 402 back in if I don’t sell it, or de-tune the LS7 a bit with a mild hydraulic roller.

I am taking a lot of measures to try and keep from overpowering the chassis with intake selection, cam selection and cylinder heads. It’s basically a drag build that should spin 8000 when it matters. We’ll see how theory meets reality haha.

The chassis is really well sorted. I’m working on some brake stuff in the background that I’m not ready to show yet, and I have some plans for improved cooling but requires me to move my relay boxes in the bumper.

The car really is fantastic right now. Zach from TST wants to drive it haha only Matt drove it back in the day. We need to hit the canyons soon once riots stop maybe. Not going anywhere near LA or the beaches until this stuff blows over.

[largeorangefont]

It will never be a drag radial only car don’t worry!

No way you’re not being a dick at all. You’re just being honest. I’m pretty pragmatic about the LS7 and how I’m almost only going to make it objectively worse lol and that’s why I’m keeping the LS2 combo going at the same time. The engine build is a dream fulfillment thing and is not exclusively built for the FD, and Texas Mile in this car is kind of like a bucket list deal. Even if I don’t hit 200 running 190’s would still be a hell of an experience.

This is a race engine I’m stupidly putting in a street car and it’s going to be entertaining, probably suck to drive, and be fast AF. For all I know I’m going to get impounded by OC Police as soon as I turn onto the street just for the loud idle lol.

Long term I’ll probably build a mild ls3 short stroke engine for it, put the 402 back in if I don’t sell it, or de-tune the LS7 a bit with a mild hydraulic roller.

I am taking a lot of measures to try and keep from overpowering the chassis with intake selection, cam selection and cylinder heads. It’s basically a drag build that should spin 8000 when it matters. We’ll see how theory meets reality haha.

The chassis is really well sorted. I’m working on some brake stuff in the background that I’m not ready to show yet, and I have some plans for improved cooling but requires me to move my relay boxes in the bumper.

The car really is fantastic right now. Zach from TST wants to drive it haha only Matt drove it back in the day. We need to hit the canyons soon once riots stop maybe. Not going anywhere near LA or the beaches until this stuff blows over.

I know you know what you are doing. I totally get the dream and goal.  We absolutely need to go for a run one day soon here.

[paul_3rdgen]

I'm loving this because I've been debating on stroking my LS2 to solve my reluctor wheel issue, and the fact that I could make more power makes it more appealing.  I can keep my top end as is.

Short vs long stroke is a very interesting comparison.  4" stroke vs 3.622" is basically like spinning 10% higher RPM all the time.  Expect to pull the peak power down by 400-500 rpm or more, and fall off sooner due to airflow restriction and port tuning.  Without a big cam it can be hard to make them rev happy.  A 4" bore also makes it tough to get good airflow due to valve shrouding unless you stick with cathedral port heads, but then you pretty much need to step up to a 235-245cc intake port minimum to have enough airflow for the displacement.  For the cam to behave similarly as what you have in the car now you can expect to add about 4-6* duration to the intake, and retard the cam timing a bit.  If you keep the same cam it will behave like a milder cam for peak power location and driving around.

It depends what you're looking for.  If you want an engine that will beg you to wring it out to 7200 rpm every shift a 402 possibly isn't your best route.  My second little horsepower bump comes in at 6250 rpm which I'm very happy with.  There's a thread on ls1tech that documents dozens of 402-408 builds and you'll see most are HP peaking at 5500-6000 and make less horsepower than your LS2 does.  We've learned a thing or two since 2007, but this is a great reference for you to compare against your LS2.

https://ls1tech.com/forums/dynamometer-results-comparisons/816128-408-results-part-ii.html

That said, HPR is dominating the road race world by building induction limited 468 motors that make "crap" peak power compared to their potential, but make so much damn midrange power that they pull on literally everything else on the track.  These are 900 horsepower capable engines that are  induction limited to ~6000 rpm - but live forever on track, use big maintenance free hydraulic roller cams, and out accelerate everything.  It isn't a traditional sports car power delivery, but if you're motoring past exotics tractoring around at 5500 rpm do you really care?

A 427 or 440 can definitely be the high reving screamer engine for you though if you want to make big power - so maybe think about sleeving your block.  The 4.125" bore is a game changer, and even with a relatively small cam you can make them rev out to 7200 and make huge power.  The ls2 block is RED's preferred block for doing darton sleeves - best strength in the block and performance is the best with the bay to bay breathing.  Exidous is building a darton sleeved motor right now.  My build is starting with an LS7 block because I found a SBE for cheap.

Now, when people trash talk stroked LS2's based on dyno numbers there's a factor to it that people don't understand.  There are intangibles to having the larger engine that you just don't see on a dyno.  It is more powerful everywhere, all the time.  Part throttle power and driveability is better and stronger.  Throttle response is stronger.  They hit harder.  Bigger cams drive easier.  Average power is going to be WAY better as well.  Managing the torque in the midrange can be tough with such a light car, but with your widebody and everything else I have no doubt you could handle as much power as you can throw at it.

You're making fantastic horsepower with the LS2 already and honestly if you keep your top end and you build it into a 402 I wouldn't put the expectation to gain toooo much peak power unless you really get after the camshaft.  What you would gain is at least 40-50 ft lb at the tire and the car would be a freaking animal.  If built right it can be very durable - I'm at about 22,000 miles and showing no signs of wearing out - and I beat the crap out of it.

Wow!   Thanks, that helps a lot.  Tons of good info, and I’m learning.  I’m in no rush and need to plan it out properly obviously, I have ideas in mind but this info you provided will really help. 

Track day This Saturday and I’m excited to get out there! 


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[kinger]

I want a 4.125+ bore engine so bad but LOF advice is solid.  I will put some top shelf Mamo
Heads and a proper NA cam someday and call it good.  The balance is sooo good right now at 430whp on the heartbreaker dyno.  If I can eek out 500-510whp I’m done.  Perfect for this car.  I just want to put the dang HPR 7.7 L in just cause of the sevens lol.  Dumb, expensive, and I will probably just stay with 6.3L. 

Love this build so much!!  22,000 miles is good!  I have around 20k on mine now too.  It’s just feeling better and smoother now that I have been playing with HPtuners more.  Dialed in my rolling idle dip today!  Such a nice car!!


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[largeorangefont]

I want a 4.125+ bore engine so bad but LOF advice is solid.  I will put some top shelf Mamo
Heads and a proper NA cam someday and call it good.  The balance is sooo good right now at 430whp on the heartbreaker dyno.  If I can eek out 500-510whp I’m done.  Perfect for this car.  I just want to put the dang HPR 7.7 L in just cause of the sevens lol.  Dumb, expensive, and I will probably just stay with 6.3L. 

Love this build so much!!  22,000 miles is good!  I have around 20k on mine now too.  It’s just feeling better and smoother now that I have been playing with HPtuners more.  Dialed in my rolling idle dip today!  Such a nice car!!


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I think we gained you like 100 HP to the ground talking you into putting NT01s on the car

[MPbdy]

I want a 4.125+ bore engine so bad but LOF advice is solid.  I will put some top shelf Mamo
Heads and a proper NA cam someday and call it good.  The balance is sooo good right now at 430whp on the heartbreaker dyno.  If I can eek out 500-510whp I’m done.  Perfect for this car.  I just want to put the dang HPR 7.7 L in just cause of the sevens lol.  Dumb, expensive, and I will probably just stay with 6.3L. 

Love this build so much!!  22,000 miles is good!  I have around 20k on mine now too.  It’s just feeling better and smoother now that I have been playing with HPtuners more.  Dialed in my rolling idle dip today!  Such a nice car!!

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I think we gained you like 100 HP to the ground talking you into putting NT01s on the car

Now that's the truth!  Lol!

Thanks for the kind words Kinger.  You can definitely make some good power with your 383.  From what I remember it isn't really optimized right now. 

[Exidous]

I want a 4.125+ bore engine so bad but LOF advice is solid.  I will put some top shelf Mamo
Heads and a proper NA cam someday and call it good.  The balance is sooo good right now at 430whp on the heartbreaker dyno.  If I can eek out 500-510whp I’m done.  Perfect for this car.  I just want to put the dang HPR 7.7 L in just cause of the sevens lol.  Dumb, expensive, and I will probably just stay with 6.3L. 

Love this build so much!!  22,000 miles is good!  I have around 20k on mine now too.  It’s just feeling better and smoother now that I have been playing with HPtuners more.  Dialed in my rolling idle dip today!  Such a nice car!!

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I think we gained you like 100 HP to the ground talking you into putting NT01s on the car

Now that's the truth!  Lol!

Thanks for the kind words Kinger.  You can definitely make some good power with your 383.  From what I remember it isn't really optimized right now.

For sure. If he put some Mamo 220 or 235's on that motor it would be a BEAST.

[kinger]

For sure on both tires and better heads/Cam.  I should have bought Exidous MMS heads but I wasn't ready and I hate it when stuff sits around and collects dust.  Someday! 

[MPbdy]

https://youtu.be/eb7xar-1QXM

Took some video playing around last night   The stretch of windy road I used to take much faster, but last time I went through there a bunch of people were parked for watching the sunset and some dude was walking his dog.  Felt pretty bad lol.  It is a hell of a road though - reminds me of Laguna Seca through there.  There are a couple drops just like the corkscrew.

[Exidous]

Got a little wiggle there in the braking.

[MPbdy]

Got a little wiggle there in the braking.

Yeah it did lol I'm thinking I need an alignment.  The car hasn't felt as sharp up front since I put the 18's on.  Either that or the 275's are too much tire up there on a 9.5" wheel.  It is a little vague on center, but tracks super straight so I'm not too sure where to look other than starting with an alignment check.

Was trying to get a couple datalogs out to 7k in fourth which is not the easiest thing to do.  Drove it a little deep maybe.

The AFR on my sensor is reading 11.5 average under power and they told me it was 12.5 on the dyno.  Not sure where the delta is coming from.  I'll check it on the gauge instead of just reading it in HPTuners maybe my calibration equation is wrong for the sensor, but it seems right at 14.7.  Might not have been a great reading at the tailpipe.  Fueling is flat and consistent, just too rich.