My car: 95 A4 Stock 48K most recent 12K put on by me over past 9 months.

My use: Daily Driver 50/day mixed driving no drag strip (some road course) Morning drive 25 miles of bumper-to-bumper 10 - 30 mph
Evening drive 25 miles at 75 - 90 mph

My goal:I would like 50 - 75 more HP over a broad rpm range (low to middle rpm rather than middle to high rpm. The car must not suffer in realiability or street drivability. It needs to be able to sit in stop & go traffic and idle smoothly but still be able to rev to 6K.

My plan: completely n/a I would like to eventually do a package consisting of:
port & polish of stock heads or perhaps port & polish LT4 heads?
cam (here is where I need some basic guidance)
LTs, RT cats, stock exhaust from cats back (some stealth) I'm guessing that the stock mufflers can handle the additional flow and sound a bit better

My questions:

What portion of the cam profile determines smooth running streetability vs the engine dying at a stop light. Is it duration of lift?

Is it best to have the shop doing the port & polish, to "custom grind" a cam for me or buy a cam from a specialty mfg?

Where can I go for some basic information on cam selection(I have searched the forum) & tech faq but not found the answers.

Thanks for any education & suggestions

 

Hotcam, tried and true, and no problem with driveability. Its usually the LSA that effects lopeyness and alot of lope will make the car want to die at the light. Too much duration will have a the same effect. So while you can go bigger than Hotcam and personally I would (because lopeyness is something I like), you dont want to go too much bigger.

P&P the stock heads, they'll end up flowing better than the LT4 heads. I recommend stiffer springs than what is recommended for the cam, whichever you pick.

Look on my site at Nathan Plemons' dyno results.

 

50-75 hp And driveable will be pretty hard to gain with just a Cam swap. Normally the trio of Cam, heads, and headers will yield a good honest improvement over the stock setup.

#1 Best thing you can do is to see what the other guy is doing. Some, like me, will experiment this component or that component. But just look at what other's are doing, find out what you like and copy.

#2 you can play around with sim software to give you an idea, but it rarely gives you the final picture

Since your car has a MAF sensor, rather than a MAP sensor, it should be able to keep with most cams upgrades.

Go to www.compcams.com for info on cams. Pay attention to the 218/224/230 cams with the 112 LSA

Before you look at which route to go with for heads, ask yourself what will you want in the future. Porting your stock heads is a great start, but there are other more powerful solutions.

 

Hmm I thought that I was clear in that my PLAN is to do all 3 as you mention; p&p the stock heads, streetable cam, Long Tube headers with random flow cats.

I'm not sure what you mean by the second part "what will you want in the future?" I would like an increase of 50 - 75 HP for the future & no forced induction.

You indicate that there are other more powerful solutions that to port my stock heads. What might I have overlooked?

THANK YOU for the tip about comp cams website

 

If you are going to port the heads, do that first. Have the heads flowed, then pick your cam. If the heads flow well on the exhaust side, you will want to pick a cam with a similiar intake and exhaust duration. If the exhaust is high 60 to low 70% intake/exhaust choose a cam with approximately 6 degrees more duration on the exhaust side.

If you want a smooth idle, a lobe seperation of 114 will be a good choice. A cam that would work well for you is the LPE 74211. It will give you the low and midrange you're looking for with a smooth idle.

Good luck!

 

Yes.

Find a shop who has a good track record with porting LTx heads then ask them these questions.

Go check out the LT1/LT4 forum on camaroz28.com. Lots of good engine building info over there.

If you search over there in "LT1/LT4 tech" and "advanced tech" you should find threads about this sort of basic information, including pointers to other resources on the web and in books.

 

hi
if you want a top engine builder contact harold at port pros in TX. tell gene told you to call. harold worked for some of the top engine builders in the country. he building a supercharged lt4 for me right now. believe me if he wasnt good he would not be doing mine. portpros.com