403 LS2 FD - LS7 Build for 2020!

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Awesome update.

A few comments -

You live down in OC now?

How much oil are you running? I run 1 quart extra and have not had an oil pressure variation that I have noticed ever. My accusump has never activated on the track. I find that a little odd myself, but I will take it.

R888s suck on the street compared to NT01s and the RC1. RC1s have slightly better street manners than the NT01, but if you need tread, the tradeoff is worth it. I've got caught on the freeway in a downpour twice with my RC1s.. that was not fun.

Also RC1s hate being slid or spun. NT01s love it.

I am at a similar point with cooling, I think I have plenty of cooling capacity, but I need to improve the air management and vent the hood.

What brake pads are you running now? Yea, you need more rotor mass. I'm going to go to a new front caliper at some point because I'm starting to flex the OE calipers, you probably are too, but to a lesser degree.

[MPbdy]

Yeah!  I've lived in Irvine for the past couple years, and just bought a condo in Orange just a little West on Chapman from Jamboree.  We have a 2 car garage and a 2 car driveway now!  It will be a godsend when everything is setup.  It is a straight shot for me to head up into Santiago now   Living ~1 hour without traffic from my dad's garage has put a damper on working on the cars a bit which made all the failures even that much more frustrating, but it is a lot nicer than Fontucky area.  Just expensive as hell.  Next move for me may very well be to the Carolinas where I can put up a barn and own a brand new house on an acre for 2/3 what I paid for a condo.  I dream of having a chassis dyno in my backyard to start dicking around with, and a nice little clean room to build engines.  It is like heaven out there for drag racing too.

Oil I keep right around full on the dipstick.  I notice a lot more oil consumption when overfilled, and my concern is I don't really know where it is going.  I don't want to be ingesting oil.  I recently vented my PCV and my oil control got a LOT better.  I just stuck a filter vent in the oil fill cap for now I'm not even running a catch can.  I've only puked oil that one canyon drive I did where oil got SUPER hot, and I was overfilled.  Next time I'll wrap a rag with a zip tie and see how it does.

I do put at least a half quart to 1 quart extra when I know I'm really going to hammer on it.  I just dump whatever partial open bottle of oil I keep in the bins for top ups so the amount varies.  I used to have stable oil pressure down until 1 quart low, but with the slicks I've seen flutters both turning and in a straight line with as little as 2/3 low.  This thing really boogies on the street now.  The real reason for the dry sump is the LS7 build and the RPM I want to turn, which to sum up in a couple words is just pure ignorance.

I definitely had to Uber to work a couple times this year when I only had my RX7 to drive lol...it rained fairly often at the start of the year.

Brake pads I'm actually having great luck with EBC Yellows other than I went through the fronts in 3000 miles.  They don't squeal, they work from cold, and I've thrashed them very hard on Angeles Crest and I lived to talk about it.  There's just not enough pad area to get sufficient service life, and the rotors are too small.  Unfortunate law of physics is that velocity is far more impactful than mass when it comes to stopping vehicles.  The light weight helps, but the speed is what gets you.

I did pick up a set of 4 piston Cayman S calipers for a steal from a Porsche dismantler.  I'm going to try and put together a budget kit at some point...if I use a production CX9 rotor I'll have less than $1000 into them including 12k mile calipers.  The calipers are way bigger than I expected though and I think I'll still have clearance issues with my RPF1's.  I still have some of my old Stoptech excel spreadsheets used to science out piston sizes and such, and they're actually a surprisingly good match for the car with the 949 master cylinder for fluid volume, and brake bias will be close enough to keep using the factory prop valve if I move the rear caliper out a bit.

[paul_3rdgen]

Great updates and a lot of good useful info!  I still don’t understand why you didn’t buy the brake kit you put together, stopping with ease is so satisfying.  And your right, you would think Samberg would of spent more time in nailing down one of the most important items of the swap, the bump steer issue. 

I really hope your wrong about the eaton true trac, just finished my diff swap and I didn’t get a chance to drive it much to notice an issue.   

Btw, you’ll love a drysump as the 8-10 litres of oil will help with cooling and you’ll need it with all the grip and power your planning.  I really appreciate your honest updates, it helps us all to improve these awesome cars! 


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Drop me a line sometime if you want to do a canyon cruise I am not too far south on the 5.

You pretty much need to run an extra 1/2 to full quart in a wet sump LSX to keep from starving them at the pan in a road race scenario.. It is pretty much the lesser of all other evils. Now that I am fully vented with no PCV, I consume a slight amount of oil, and I know its not going through the intake like it was before.

The only way to drive these cars is with 100 treadwear or less tires I have some 200 treadwear Hankooks I use for storage and putting around.

[largeorangefont]

Great updates and a lot of good useful info!  I still don’t understand why you didn’t buy the brake kit you put together, stopping with ease is so satisfying.  And your right, you would think Samberg would of spent more time in nailing down one of the most important items of the swap, the bump steer issue. 

I really hope your wrong about the eaton true trac, just finished my diff swap and I didn’t get a chance to drive it much to notice an issue.   

Btw, you’ll love a drysump as the 8-10 litres of oil will help with cooling and you’ll need it with all the grip and power your planning.  I really appreciate your honest updates, it helps us all to improve these awesome cars! 


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My Truetrac has been completely smooth. They function similar to a Torsen T2R, but the T2R has an even high torque bias ratio because it has preload in it.

That was probably the notchiness he felt in his T2R. Sometimes you can feel these torsen diffs transferring torque from one side to the other if you are on inconsistent pavement, or if one tire is in the wet and the other is in the dry. That "wagging" gets worse the more torque bias ratio you have in the diff.

That is why I've always recommended the Truetrac to the people here. It will feel very similar to the original FD torsen diff and operate quietly and smoothly. It is not quite as aggressive as a T2R, but is stronger and has a better price point.

[MPbdy]

Great updates and a lot of good useful info!  I still don’t understand why you didn’t buy the brake kit you put together, stopping with ease is so satisfying.  And your right, you would think Samberg would of spent more time in nailing down one of the most important items of the swap, the bump steer issue. 

I really hope your wrong about the eaton true trac, just finished my diff swap and I didn’t get a chance to drive it much to notice an issue.   

Btw, you’ll love a drysump as the 8-10 litres of oil will help with cooling and you’ll need it with all the grip and power your planning.  I really appreciate your honest updates, it helps us all to improve these awesome cars! 

Thanks man!  It is hard to explain why building a swapped car is harder than just bolting the engine in.  Until you've gone through it I don't think you get it.  Every single major system on the vehicle has been highly modified and has next to no R&D behind it.  Things can and will go wrong.

I really wish I had bought one of those StopTech kits while I had the chance, but they don't fit behind a 17" RPF1.  I had a trophy kit on my C5Z so I know what I'm missing...they're phenomenal brakes.  I honestly would've been fine without a parking brake too.  I'm so hesitant to change to 18" wheels and tires since my RPF1's have been so good to me, tires are super cheap, and the wheel/tire combo is unbelievably lighter per corner than an 18" setup.  That pushes me toward wanting mega baller forged 18" wheels that're still heavier than what I have, and are hard to get excited about financially.

About the diff, like LOF said the Eaton is probably better than the T2R was for driveability, plus my T2R preload clutches were worn out which...who knows how that impacts the behavior of the diff.

There are far too many good reviews of the Eaton diffs for them to be a problem.  Immediately though after switching to the clutch diff the intuitive driving came back, it drives straight in wheelspin, and I can hoon the thing anywhere I want as aggressively as I want.  The time I spent with the Torsen was the only times ever I found myself somewhat out of control hooning the car because of how it over grips and then snaps loose once the bias ratio is reached.  By the time the tires break loose you have way too much power applied.  The solution is to just be harder on the throttle to avoid that grey zone of having traction, but I prefer to progressively roll into wheelspin rather than punch it and back off.  The T2R has a super high bias ratio which exaggerates this behavior vs the Eaton which is probably less than half the bias ratio of the racing diff.  I have just found that I have a strong preference toward a clutch pack style.  I grew up racing Karts so I'm used to driving with my right foot. 

Buying a super cheap used T2R was probably just a dumb experiment all around.  So far I'm very happy with the cobra carbon clutch pack diff, but I haven't put enough miles on it to burn it up yet so I'm not sure how long the honeymoon phase will last.  If I do wear out the clutch pack I'll either just throw in another new one for $200 off Amazon.

[MPbdy]

Drop me a line sometime if you want to do a canyon cruise I am not too far south on the 5.

You pretty much need to run an extra 1/2 to full quart in a wet sump LSX to keep from starving them at the pan in a road race scenario.. It is pretty much the lesser of all other evils. Now that I am fully vented with no PCV, I consume a slight amount of oil, and I know its not going through the intake like it was before.

The only way to drive these cars is with 100 treadwear or less tires I have some 200 treadwear Hankooks I use for storage and putting around.

Yeah I'd like to!  I have it parked at my parents for now while I get done with the move.  This will be the first time in 2 years I'll have access to both my daily and my FD...I've had to make the commitment to drive it sometimes 4+ weeks at a time if I want my FD in Irvine (which I've done a lot of haha).  So stoked to be able to keep it at my own place in a garage and take it out whenever I feel like it.

Now that I know about it, I'd really like to get the fuel leaks fixed in the trunk too..but I'm still trying to decide how to tackle it.  I'd feel really dumb if something happened and I knew about the leak.  Maybe I'll try to just band-aid it until I take the car apart.  No joke my pass-through for the wiring is insulated with JB weld...I could just gum it up with more putty and it'd probably last another 4 years.

[paul_3rdgen]

Don’t be lazy!  Fix the leak.  No matter how complete we think we have these cars, they are always a work in progress.  We are building a very fast car on a budget.   Lucky that we have this forum with enough knowledgeable people to bounce ideas off of!   Best forum out there, I haven’t been contributing much lately but always here to help if someone needs. 


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Gum it up and run it

[kinger]

Great update!  Its about time you got on the keyboard LOL. 

I thought halfspecs car was perfect, and still amazes me how much refining a old car costs.  My list never shrinks LOL.  I must have a bumpsteer issue on mine to as to why it feels twitchy.  Added to the 'list' 

The 428 build sounds awesome!  I have been fantasizing about ITBs but it appears to be a solid uphill battle and may take the car in the opposite direction of 'refined' from my 'ferrari like' fantasy to more of a finicky race car.  I'm having to reel in my plans for the car and focusing on driving it more!

[wickedrx7]

Great update and great to see you keeping up refining the car!  A few notes, lots have been discussed already but just to add my $.02. 

1 - Cooling System - I added a little extra ducting to direct the majority of air through the samberg setup and saw minimal difference.  Halfway down the page here - https://www.norotors.com/index.php?topic=19354.60
My opinion is that the samberg radiator core is subpar.  I think it is cheap and isn't up to the job to cool a large cube V8.  Even wit everything ducted, this doesn't cool anywhere near as good as my previous HOWE radiator.

2- I too overfill mine by about a quart for track days.  I do see increased usage but nothing to be supper worried about.  I have yet to trigger my accusump or see any drops on pressure.  I should note that I am not running slicks...

3 - I love my Truetrac and have absolutely no complaints.  It acts just as the stock dif and gives me the utmost confidence in power-slides.  My car is unbelievably predictable and confident inspiring with the ass hung out.  So much so that it will probably get me in trouble one of these days. 

Very interested in seeing your brake setup and am curious to see how the RX-9 rotors handle track use!

[MPbdy]

Great update!  Its about time you got on the keyboard LOL. 

I thought halfspecs car was perfect, and still amazes me how much refining a old car costs.  My list never shrinks LOL.  I must have a bumpsteer issue on mine to as to why it feels twitchy.  Added to the 'list' 

The 428 build sounds awesome!  I have been fantasizing about ITBs but it appears to be a solid uphill battle and may take the car in the opposite direction of 'refined' from my 'ferrari like' fantasy to more of a finicky race car.  I'm having to reel in my plans for the car and focusing on driving it more!

I sit around and dream up engine ideas, many related to the intake, and then I pop the hood and get a quick reminder of just how premium the real-estate is under that hood line.  The issue really is even if you got the nerve to hack up a hood and run something above the hood line it looks super goofy because of how far forward the engine protrudes, or rather how short the nose of the car is.  There's like a whole 2 feet missing off the front of the car compared to a vette.  I've yet to see someone really nail a cowl or bubble hood either.  The tightest clearance is basically at the same point as the headlights which is right where the bumper starts...doesn't help that all the body lines are so rounded there's no natural area to "bump" up.

I think there's a way to do an ITB setup but it wouldn't be optimal for performance unless you're spinning 8000+ rpm...I still have my thoughts on how to do it though...

My issue is I can't find throttle bodies off the shelf that are big enough.  An LS7 intake valve is 2.200" diameter...I don't want a throttle body with a tighter choke than my intake valve.  The biggest OTS kit I can find is 55mm (2.165"), but the intake manifold design wouldn't work for these cars.  Really need like 63-65mm (~2.5") throttle bodies for an optimal setup imo.  That steers toward someone like Kinsler that will build you whatever you want, but is going to be mega expensive even if you just buy the 8 throttle bodies from them and build everything else custom.

[kinger]

Pantera EFI makes a 2.5” kit fir about $3700 but its for cathedral port heads.  He make a square port. 

52mm have made 700hp on a engine dyno on a 402.  Not sure how much power you are planning on.  With a fast 102 as the max under hood option feels like we are limited to around 650hp before it lops off air flow. 

My idea on the ITBs was a harrop set up and cut two “rectangles” in the hood to show the recessed horns and make a clear plexi plate that had holes/slots in it to keep out major debris.  The front horn i think would stick above the hood line about 1/2” though. Its soooo close to fitting.  Here is the set up in a fbody.




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[MPbdy]

I've been to Pantera's shop in person it is literally 2 miles from where I work.  He does have LS7 ITB setup...well designed, but very long runners.  Not something we'd be able to package easily.

We actually have very good cowl clearance compared to Fbodies and Vettes.  It is the front of the hood that gets so low and short for us.

I would want something in a similar footprint as the Holley Sniper with a common plenum and a front feed inlet so you can run an actual air filter.  The other thought is some kind of non-hideous cowl hood with some kind of air filter and a hood seal.  I would never run my car without air filters like so many people do.

The only way I could justify an ITB setup would be to buy the throttle bodies on the cheap and try to make the manifold myself.  I can't see spending super charger money on an ITB setup.

It isn't so much the peak power that they've made, but the dynamics of the intake tract.  The ones I've seen on LS7's have had very odd double hump torque curves and don't seem to make as much power up top as they should.  You can make 700hp through a FAST also, but it is definitely not optimal.

[paul_3rdgen]

I’m all about trying different things but why go through all the trouble for the itb’s.  Not worth all the work involved, especially when it’s possible to make 650rwhp Na without them.  Just my opinion.


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