Looking for good advice from guys that either done a build like this before or know first hand of a build like this.

I have a c5r 427 that I'm looking to have redone/freshened up. The question is what head to put on it? Some say cathedral others are pushing for rectangular style.

What do you all have to say?

Thanks in advance!

 

Why not LS7's?

 

Kinda leary with valve issues.

 

Are you talking OEM castings then? I assumed with a C5R, aftermarket castings were an option.

I'd still lean towards LS7 heads, they're similar to C5R heads anyways. I see them go for ~$1k in the classifieds pretty often. New exhaust valves, guides, and machine work is maybe $500 tops and you keep the titanium intake valves.

 

Intended use and budget would be helpful to offer suggestions.
However with a 4.125 Bore or larger I would start with the
TFS LS7 Heads, Great Flow and value in a 260CC Intake Port
Volume that rivals a WCCH Ported OEM LS7 with the valve
Issues addressed in a 280CC Intake Port.
In a Cathedral MMS 250 with MAMOFIED FAST 102, NW102 TB would offer
Phenominal throttle response and only give up @ 6500+ RPM
Considerably Greater $$$ though.
If you want to spin 7000+ RPM I would also recommend LLSR
From CAM MOTION.
Just my .02

 

No budget, want it done right. Rather have lower rpm numbers then high. I'm open to oem or aftermarket. Car is street/strip. Not a daily driver at all. Pure fun and smiles.

 

IIRC the car is an F body currently running a TR244 cam and stage 3 TEA heads.....certainly a no slouch combo to begin with.
Since you already have a ported Fast cathedral you may just want to go with a killer aftermarket like Tony Mamo's new 235 heads. For max power the 250s might make more but it seems like you just want a silly street car with explosive mid range.
A Cam Motion low lash solid roller somewhere in the mid 240s duration would help you plan for a 2500-6500 power band

 

Since you have a FAST Cathedral Intake and given your goals.
MMS 235s with light valves, talk with Tony Mamo @ MMS.
LLSR from CAM MOTION something like
243*-247* Intake, 247*-251* Exhaust, ~.680" Intake,.650" Exhaust
LSA 114*+2*-3* . Rip your face off throttle response from 1500RPM,
560-580 RWHP @~6500 RPM, Pull to 7000+ RPM with very little
Fall-Off, and great low speed Driveability, talk with Kip @ CAM MOTION.
you will be very happy, Guarenteed!

 

OP.....What is your target peak power realistically?

What would you be pleased to see in terms of peak power be it at the flywheel or rear wheel (keeping in mind chassis dyno numbers vary alot more than engine/flywheel dyno numbers due to a host of variables in driveline mass and parasitic losses).

Once that question is answered I can tell you if a package like you describe is even possible (BIG power never comes with good low/midrange power and excellent drivability).

I'm thinking my new MMS 235 is exactly what your after....or should I say do exactly what you want but need to confirm how much power your hoping to see to know if a package built around these heads will suit your needs.

Don't forget everything is a trade off of sorts so focus on the part of the power curve your most excited to see beefed up.....its your car and your driving style and only you know exactly how the car will likely be used.

Not to mention it makes sense financially to stick with your current cathedral induction and based on what you described I think a killer highly optimized cathedral head might just cover all your bases.

Check out this thread if you haven't already

https://ls1tech.com/forums/generatio...ts-235-cc.html

Cheers,
Tony

 

Since you're in the Houston area.

What machine shop are you using that will do all of the above for 500 bucks??

 

Are the TFS LS7 heads available? I know they have been discussed on the forum, but do we have any proven results?

 

Advertised on Summit, haven't checked as I have their LS3
heads (ordered just before I saw the LS7s or I would have got those)
Which have had good results. Haven't seen results on heads yet
But with a taller straighter port and only 5 CC more port volume
and Huge flow, pretty sure they will be Excellent!
I think MMS 235s would be best for OPs goals though.

 

Is it OK to quote yourself??......LOL

My reason for doing so is to also state I can also help you with ported LS7 heads or ported LS3 heads....both of which I would likely use TFS castings for (and have both on my shelf).

My reason for not originally going there is due to the fact what you described seem better suited in a really efficient cathedral.....nothing around town would feel as lively and responsive (aka fun.....tire shredder....tons of throttle response)....if we could hit your target power goal with that head it would make perfect sense for you and was the reason I originally inquired about it.....more power ultimately could be had with a properly modified square port but no square port would act the same driving around town as the smaller efficient cathedral with alot more low RPM port velocity ....hence the "balancing act" I mentioned earlier as well.

There is no right choice because any of the heads I mentioned could qualify as the right choice but there is a right choice for YOU.....and that's what I'm trying to help you determine based on the questions and response you give. What's right for you might be wrong for a different customer's needs and visa versa.

-Tony

 

I'm dumping all my 90mm stuff going with 102mm on my induction. I'm looking for good solid numbers for a car that will be on the street but I want it to rip on the 1/4 mile. I'd live to have 540 rwhp n/a.

My original post is to see what others are running or ran? Motor is out and at a well renowned engine builder and they ate going to give me their opinion on how the motor should be built. Sorry forgot to mention the car has a 3200 stall. I just want dive other opinions on other builds.

Thanks for all the good info so far.

 

What tires are on the car? Good low end/midrange sounds fun, but it's not fun when you punch it in 3rd and go sideway on the freeway. With 427ci on tap, you could probably sacrifice some of that low end for better power higher in the RPM range.

540whp should be a cakewalk with any of the heads we're discussing. I just read Tooley has a couple LS2's with As Cast TFS cathedral heads making over 500whp. A couple C6Z buddies of mine are at about 580whp with stock LS7 heads (haven't dropped a valve yet lol).

 

Cars got drag radials on.

 

curious where the engine is at ??? Thought you told me the car was @ West Bend dyno..???

 

Cars at wbd. Carl Wegner @ Wenger motorsports has the motor.

 

Anything close to 500 RWHP (or more) will rip on the quarter mile. Especially so with that type of number thru a stalled auto which is a bit more challenging (I think most of the long timers on here that have seen countless stalled auto results would agree 540 at the tires is pretty stout).

Problem with big numbers thru a stalled auto is the efficiency of the converter....my guess is it would take anywhere from 670 - 700 at the crank to hit that target.

If truly nailing that goal or getting damn close was of high priority, I would probably modify a set of 245 AFR castings for you to nail that number (365-370 CFM) and it would still be very responsive and make the power your looking for if the build went together right. It would still be a build with a focus on a high air speed port design to boost the bottom of the curve but also supplying enough air to support the power we need to get you into the mid 550 range at the tire (depending on how stingy or optimistic the dyno is....another big variable).

I built this years ago.....made 680 at the crank and 600 ft/lbs.....I had the pleasure to drive this engine in the C5 it was installed in and it really ripped and had tons of top end pull. With some additional tricks and tweaks garnered over the last few years, your build could potentially be better. Its a 434 but a 427 would be very similar

Here is a link with all the info

https://ls1tech.com/forums/dynamomet...afr-245-s.html

Once again....its really about which choice makes the most sense for you. My new 235 would boost the bottom some no doubt but its a stretch to make 540 RWHP thru a stalled auto (they just never look good on the chassis dyno as a general rule).....although with an optimized set-up, the right tune, the right converter, and a typical Dynojet number I think we could legitimately get there but without the perfect trifecta of all the items mentioned its more difficult.

The Mamofied 245's breath deeper and will make more top end power.....lower RPM snap will be effected but not dramatically different....hence the reason you might consider them. I think the trade is good....meaning you would certainly get a nice bump in the top end charge and only give up a modest amount of lower RPM "crispness" in the throttle. Unlike moving into a larger cam which typically only gains you a little at the expense of alot (low midrange torque, part throttle tip in, idle quality etc.)....those types of trades you have to think harder on.

Hope this helps

-Tony

 

Thank you Tony.