86 IROCZ28

Thinking of getting a new engine in my Camaro and am wondering if to go with a 350 or 400. They go for around the same price here so no big deal there. The only thing that I am worried about is will the TPI be able to feed the 400?

Will it be much more work in the long run to get the motor running optimum compared against the 350?

What else would need to be changed if going with 400? I know the chip would have to be burnt, anything else?

Do headers for 350's bolt up to 400s?


Mike

IrocZS383

I am in the process of building a twin supercharged 427 with TPI induction. The heads I am using flow 389 cfm. I will have to modify the base and runners to feed that much air but it will still work on my engine. As far as I know the stock tpi will feed a 400 small block. TPIS has used their Big Mouth base on a 400 and got 440 hp. You might want to use semi siamese runners from AS&M or full siamese from SLP. The mod I am doing to my base is something I found on this board. Search for modified tpi, what I found was to cut out the divider after the runners about 5". This allows both runners to feed each intake port. The guy who did it put it on a 305 that only reved to 4800 and after the mod reved to over 7000 because of the increased airflow. The semi siamese runners will reduce your torque which you will have plenty of with a 400. I think the headers will fit depending on which heads you have. Hope I helped some.

IrocZS383

Sorry missed the part about the chip, you will need a new chip and new injectors. I am using the Accel DFI Gen VII, but thats an expensive proposition. It shouldn't cost too much more as long as you use the same type parts in either one. Stock vs. stock or aftermarket vs. aftermarket. The modifying the base can be done by you with a dremel tool so that would save some money there. I think I got it all this time. Hope I helped.

the roc

ZS -- 389 cfm of flow ain’t happening from a small block head that you can bolt a TPI base to (standard 23 degree head & intake),, and can barely happen from a set of heads that can be bolt on a SBC. I thought that you may have made a typo until I saw that you think siamesing the base on a 305 can take it from 4800 rpm to 7000 rpm.

u r sofa king we tah did

twin supercharged 427? so your going to run two centrifigal superchargers? why? thats a complete waste of money. not to mention the hell youd have plumbing and mounting both superchargers. theres no way you could have that much flow out of standard heads. 18 degree is even pushing it. i dont know where your getting your numbers and info but it sounds like a load. but to answer the original question, id get an aftermarket base and some good runners for the tpi on a 400. a 400 isnt a rev machine, it does real well with a nicely matched tpi setup. massive amounts of torque.

86 IROCZ28

Thanks for the input guys. So basically an aftermarket base and some bigger runners and it should be okay. That don't sound too bad at all worth considering if to go with 350 or 400. I thought maybe the 400 would cost a lot more to set-up but seems as it may not be all that bad.

thanks,
Mike

turningfast

WOW 389 cfm out of small block heads? That is better than a big block large rectangular port aftermarket aluminum head

camaro-mayhem

oookkk...unless i missed something,a 427 is a big block,so he could have 389 cfm of flow or whatever with a reeeeaaallly nice set of heads.Dual supercharged? All i got to say is D@MN thats a lot of power!!!

smokin87iroc

i want to correct you
i am the one with the 305 that siamesed the intake in about 4-5 inches. i'm sure you can rev the motor to 7000 but you could do that before the mod. all it does is moves your power band up a few hundred rpm because it makes the tpi base act more like a lt1 intake. you got the part right about 2 runners being able to feed one intake port but you will not see huge gains unless you go to a bigger cam and need the airflow. i wanted to bring my rpms up so that when i get gears i'll be able to use them better. plus i ported my heads and put a lt1 cam in it.
you can do the search and see my pics of the port work
i have yet to go run at the track with the new setup but i feel like i should be in the high 13s
Andrew

IrocZS383

Sorry about that Andrew, maybe not best choice of words. I was just telling him that two runners would feed one port because that is what I need it to do. The 427 is a small block 4.125" bore, 4" stroke. The heads are Arao Engineering 32 valve heads. Check out the website. Don't want to take up 86IrocZ28's post anymore with my info. If anyone has any questions on my setup email me at IrocZS427@aol.com. See ya

smokin87iroc

thats ok i just don't want people to get the wrong idea that siamesing your intake will give you enormous power
Andrew

RedIrocZ-28

Ahhh yes the Arao heads. I can substantiate that 389 cfm claim. Its true. Anyway, yes the TPI will support a 400 SBC. Don't expect to rev to 6000 rpm though.

bobs89irocz

Stock tpi only flows up to 5200rpm, and a 400 should put power to pull past 6000rpm. Therefore you have to make an intake mod in order to put up some great numbers. Like a miniram or superam