So I have been thinking about doing a 408 iron block project in my 2000 MN6. Ive been looking at the TSP 408 Shortblock w/ AFR 225 Heads. This is my daily driver which will see around 10k miles a year. I am going for the NA route (NO nos or FI), looking to get some good low end torque numbers out of this to have fun on the street. Car will see the strip a couple times a year, but no road courses.

So I have some question for the people that have done this before and can help me out. I live in California so I am a little worried about passing smog. From what I have read anything over like a 224/224 114 size cam will fail the sniffer. All the research I have done on this project and the people who have gone through with it are putting in cams from the size 240 to 260+ duration and usually they are all on a 112 LSA. Now can someone explain to me with a 408 iron block engine in my C5, will a camshaft that size pass the sniffer? Why or why not?

Can I put a 224/224 on a 114 in a 408 and have it run optimal? Would this be undercamming the motor? I understand I wont get huge numbers with this cam, but what about driveability? Will the 408 like this size of a cam or hate It? And will the AFR 225 heads like this small of a cam?

Thank you for taking the time to read my long post and all help is appreciated. Any suggestions are cool also, Im open for any ideas that you think would suit me better. Just dont tell me to go FI or nos.

 

I also live in cal and have a 402 in my 2000 frc . I went with a 226/226 lsa 112 on a 6.00 lift and it passed the snifter test. I am switching to a 230/234 lsa 114 591 lift and have been told by my tuner that with this set up i will still pass without any problem. i tend to drive about 15-20k miles per year. I think with a 224 cam you will be under camed for your set up .You will have some pretty good tq but not alot of hp i would guess you would be 450 rwhp and 500+ tq. As of now with the 226 can i have 473 rwhp and 489 rwtq. with new cam i should be at 495 rwhp and 480 rwtq. Hope this will help you


btw the 408 is a iron block and will weigh about 100 lbs more then your old motor and may make your car handle different. most people who use the iron block want to spray or go FI which is what the iron block is good for. but if you are staying n/a i would go with the ls2 402

 

I'm also having a 402 installed in my 99 FRC, and have spent time trying to figure out what cam size to run. I'm finding out that some of the outlying areas of San Diego County do not have to comply with emissions checks. I plan on verifying this today. If that is the case, I will pbobably run a cam with duration in the low 240. Have either of you had experience with this size of camshaft. How does it idle, what is the driveability at low speeds, and what rwhp/rwtq #'s does it produce in a 402 w/225AFR's, long tube headers and a Fast 90??
Any input would be greatly appreciated.

Thanks

 

Hey thanks for the reply, thats great info to know. Thats interesting that your running a 112LSA and passed emmissions. It seems to me on a 112 that cam would be somewhat more lopey than a 114 and would have more difficulty passing emissions. But from what your saying, you had your tuner set it up to be smog friendly? Thats cool, I might have to look into that.

The Ls2 402 is an alluminum block unlike the iron which weighs probably around 100lbs heavier. I have done research on this and everyone that has put a 408 in thier c5 that I have seen, says nothing negative about handling. They say they cant even tell a difference. You have to remember that an Ls2 402 will cost about 1k more than a 408 setup. The 402 is also tricky to install, more labor involved and needed parts, unlike a 408 which is a 6.0 liter GM truck block that bolts right in for the most part. Its a give an take situation. If I had the funds I would probably do a 402 or even a 427.

 

I have not had any experience with a cam that large. Hopefully more members will chime in and help us both out. Good luck with the 402.

 

Can I put a 224/224 on a 114 in a 408 and have it run optimal? Would this be undercamming the motor? I understand I wont get huge numbers with this cam, but what about driveability? Will the 408 like this size of a cam or hate It? And will the AFR 225 heads like this small of a cam?



That CAM is WAY to small for a 408 motor and you will be leaving a TON of power on the table as that is barely an average size cam these days in a stock cubed 346 LSX motor. A cam that small with a 408 stroker and with 225 HEADS will choke the motor and the average performance street cam for this sized motor has a MUCH BIGGER cam to take advantage of the bigger cubes and heads to make the power the motor is capable of making!

I had a 427 ironblock b/f and unless you very **** about how the car corners I really did not notice any handling difference but the C5 that it was in was more of a straighline MONSTER!! I would not hesitate about the ironblock and recommend the cam that i had in my 427 motor the old venerable work horse MTI S1 cam with specs of 244/244, .612 lift on a 113 or 114 lsa. I had mine on a A4 on a 112lsa and i loped nice and if you want more of a stock like idle go with a 114 lsa. The bigger cubes eats up a bigger cam much easier than a stock cubed motor and the type of cam i recommend for you will be a 100% streetable. Better yet, call MTI as they have a little bit of smaller cam than the one i mention that makes excellent power and will drive like stock (called i belive either the Z1 or R1 cam) yet is considerable bigger than the 224 baby cam your thinking about!

Call a TUNER who builds alot of 408, ECS, MTI, Cartek, LGM, etc., etc., tell them what your goals and objectives and usage for the car will be and they will get you hooked up!

 

Hey Thanks for the post and your recommendations. You sound like you have had first hand experience with big cubed motors . Yah I figured that would be way too small of a cam for a 408, but this whole project has to be focused not only on making big power, but trying to pass the sniffer in Cali as well. That is my question, what size cam will be optimal for a 408 and have no problem passing smog? Does that exist? This is what I need to know. I plan on calling TSP and MSI who is my tuner and ask thier opinion. I just wanted to get some real feedback from members first.

 

YOUR welcome and I would call some other top tuners like MTI (they have a great cam that should meet your goals and pass CA emissons) and also call LGM Motorsports and of course Andy at A&A corvettes in California, as he will give you the perfect cam to meet your needs, and has first hand experience with building motor combos to pass CA emissoins!!

BEST of luck!

 

A 402 block does not need that much more then the 408. I would guess about $500 more all that is needed is the valley cover, timing chain, front cover and the racetronic harness and cam sensorsors. Most of it will be included with the motor. if you relly look at the cost you will save 100 lbs which will = about 14 rwhp for $500 which is not bad when you are trying to get alot of HP from your car.
You might want to swing by Synergy one day and have a talk with Rick (owner) about it He is very good with this these type of mods and can even build your motor

 

How do you figure that? I've heard 100 lbs = 1/10, which works out to about 10 hp. So basically you're still at $100 per hp. Hardly a good deal.

Mark

 

The 100 extra pounds WILL NOT HURT the handleing at all...........have one in my 97' & my nephew just went from a stock cube to a 408 iron block as well w/o issue..loss of power vs alum........
Sorry I cant speak to the cam in CA, But I agree on talking to Andy

 

Thank you very much for clarifying the weight issue. I have been reading some of your posts about you having a 408 in your 97 and it sounds like you love it. I really do not see how the 402 can cost only $500 more than the 408. Im thinking more like a 1k, thats one reason of many why I am currently choosing the 408 Iron over the 402 Alluminum.

 

Plus after you get bored with the NA power.............then you can spray away with more comfort

 

Thats what I was thinking, or possibly lower compression and run big boost.